The heat flux through a wood slab 50 mm thick, whose inner and outer surface temperatures are 40 and 20°C, respectively, has been determined to be 40 W/m2. What is the thermal conductivity of the wood?

Answers

Answer 1

Answer:

[tex] k = - \frac{40 W/m^2}{\frac{20-40 C}{0.05 m}}= 0.1 \frac{W}{m C}[/tex]

Step-by-step explanation:

Previous concepts

The Fourier's law, states that the "rate of heat transfer through a material is proportional to the negative gradient in the temperature and to the area, at right angles to that gradient, through which the heat flows".

And we have the following formula given:

[tex] q_x = -k A \frac{dT}{dx}[/tex]

For this case we have the following data given:

[tex] L= 50 mm * \frac{1m}{1000 mm}=0.05m[/tex]

[tex] T_i = 40 C[/tex] represent the inner surface temperature

[tex] T_o = 20 C[/tex] represent the outer surface temperature

[tex] \frac{q_x}{A} = 40 W/m^2 [/tex] represent the heat flux

So then we are interested on the value of k.

Solution to the problem

if we solve for the value of k from the formula:

[tex] q_x = -k A \frac{dT}{dx}[/tex]

We got:

[tex] k = - \frac{q_x}{A \frac{dT}{dx}}[/tex]

We can rewrite this expression like this:

[tex] k = - \frac{q_x}{A \frac{T_o -T_i}{L}}[/tex]

And if we replace the values given we got:

[tex] k = - \frac{40 W/m^2}{\frac{20-40 C}{0.05 m}}= 0.1 \frac{W}{m C}[/tex]

Answer 2
Final answer:

Using Fourier's law of heat conduction, the thermal conductivity of the wood slab is calculated to be 0.1 W/m·K given a heat flux of 40 W/m², a temperature difference of 20°C, and a thickness of 50 mm.

Explanation:

The student is asking about the thermal conductivity of a wood slab, given its thickness, the temperature difference across it, and the heat flux. To find the thermal conductivity (k), we can use Fourier's law of heat conduction which states:

Q/t = k × A × (T2 − T1) / d

where:

Q/t is the rate of heat transfer (40 W/m²),k is the thermal conductivity,A is the cross-sectional area (not needed here as we have heat flux per unit area),(T2 − T1) is the temperature difference across the material (40°C − 20°C = 20°C),d is the thickness of the material (50 mm = 0.05 m).

Rearranging the formula to solve for k gives:

k = Q/t × d / (T2 − T1)

Plugging in the values:

k = 40 W/m² × 0.05 m / 20°C

k = 0.1 W/m·K

So, the thermal conductivity of the wood is 0.1 W/m·K.

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Related Questions

Donata bought 3 Apples and 5 Pomegranites at the local supermarket for a total of $16.50 Meaghan bought 6 Apples and 11 Pomegranites at the same store for a total of $35.70 How much does one Apple cost?

Answers

Answer: the cost of one apple is $1

Step-by-step explanation:

Let x represent the cost of one apple.

Let y represent the cost of one Pomegranate.

Donata bought 3 Apples and 5 Pomegranates at the local supermarket for a total of $16.50. This means that

3x + 5y = 16.5 - - - - - - - - - - - - -1

Meaghan bought 6 Apples and 11 Pomegranates at the same store for a total of $35.70. This means that

6x + 11y = 35.7- - - - - - - - - - - - -2

Multiplying equation 1 by 2 and equation 2 by 1, it becomes

6x + 10y = 33

6x + 11y = 35.7

Subtracting, it becomes

- y = - 2.7

y = 2.7

Substituting y = 2.7 into equation 1, it becomes

3x + 5 × 2.7 = 16.5

3x + 13.5 = 16.5

3x = 16.5 - 13.5 = 3

x = 3/3 = 1

A player of a video game is confronted with a series of four opponents and an 80% probability of defeating each opponent. Assume that the results from opponents are independent (and that when the player is defeated by an opponent the game ends).
A. What is the probability that a player defeats all four opponents in a game?
B. What is the probability that a player defeats at least two opponents in a game?
C. If the game is played three times, what is the probability that the player defeats all four opponents at least once?

Answers

Answer:

(a) 0.4096

(b) 0.64

(c) 0.7942

Step-by-step explanation:

The probability that the player wins is,

[tex]P(W)=0.80[/tex]

Then the probability that the player losses is,

[tex]P(L)=1-P(W)=1-0.80=0.20[/tex]

The player is playing the video game with 4 different opponents.

It is provided that when the player is defeated by an opponent the game ends.

All the possible ways the player can win is: {L, WL, WWL, WWWL and WWWW)

(a)

The results from all the 4 opponents are independent, i.e. the result of a game played with one opponent is unaffected by the result of the game played with another opponent.

The probability that the player defeats all four opponents in a game is,

P (Player defeats all 4 opponents) = [tex]P(W)\times P(W)\times P(W)\times P(W)=[P(W)]^{4} =(0.80)^{4}=0.4096[/tex]

Thus, the probability that the player defeats all four opponents in a game is 0.4096.

(b)

The probability that the player defeats at least two opponents in a game is,

P (Player defeats at least 2) = 1 - P (Player losses the 1st game) - P (Player losses the 2nd game) = [tex]1-P(L)-P(WL)[/tex]

                                    [tex]=1-(0.20)-(0.80\times0.20)\\=1-0.20-0.16\\=0.64[/tex]

Thus, the probability that the player defeats at least two opponents in a game is 0.64.

(c)

Let X = number of times the player defeats all 4 opponents.

The probability that the player defeats all four opponents in a game is,

P(WWWW) = 0.4096.

Then the random variable [tex]X\sim Bin(n=3, p=0.4096)[/tex]

The probability distribution of binomial is:

[tex]P(X=x)={n\choose x}p^{x} (1-p)^{n-x}[/tex]

The probability that the player defeats all the 4 opponents at least once is,

P (X ≥ 1) = 1 - P (X < 1)

             = 1 - P (X = 0)

             [tex]=1-[{3\choose 0}(0.4096)^{0} (1-0.4096)^{3-0}]\\=1-[1\times1\times (0.5904)^{3}\\=1-0.2058\\=0.7942[/tex]

Thus, the probability that the player defeats all the 4 opponents at least once is 0.7942.

Final answer:

The probability of defeating all four opponents in one game is 40.96%. The probability of defeating at least two opponents is 87.04%. Playing the game three times, the probability of defeating all four opponents at least once is 88.47%.

Explanation:

To calculate the probability of different outcomes when playing a video game against four opponents, we'll use basic probability rules and assumptions given in the question.

A. Probability of Defeating All Four Opponents

The probability of defeating each opponent is 80% or 0.8. Since the fights are independent, to find the probability of defeating all four, we multiply the probabilities together:
0.8 × 0.8 × 0.8 × 0.8 = 0.4096 or 40.96% chance of defeating all four opponents.

B. Probability of Defeating At Least Two Opponents

To find the probability of defeating at least two opponents, we must consider all possible combinations of winning 2, 3, or 4 opponents' fights, and add those probabilities together. Let W represent a win and L represent a loss:

P(WWLL) + P(WLWL) + P(WLLW) + P(LWWL) + P(LWLW) + P(LLWW)
P(WWWL) + P(WLWW) + P(WWLW) + P(LWWW)
P(WWWW)

We already calculated P(WWWW) as 0.4096. The other probabilities can be calculated using similar multiplication of respective individual probabilities (0.8 for W, 0.2 for L). After calculation, we sum these to find the cumulative probability, which is 0.8704 or 87.04%.

C. Probability of Defeating All Four Opponents At Least Once Over Three Games:

The probability of not defeating all four opponents in one game is 1 - P(WWWW) = 0.5904. The events in each game are independent, so the probability of not defeating all four opponents in all three games is (0.5904)^3. Therefore, by subtracting this result from 1, we get the probability of defeating all opponents at least once: 1 - (0.5904 × 0.5904 × 0.5904) = 0.8847 or 88.47%.

Can plurality violate the majority fairness criteria? (Fairness Investigation)

Answers

Answer:

No

Step-by-step explanation:

The majority fairness criteria states that a person with majority of votes should be the winner and it is not violated by the plurarity method. Rather pluarity is always satisfied with majority fairness criterion.

Tim drove 4 hours at an average speed of 60 miles per hour. How many hours would it take Tim to drive the same distance at an average speed of 50 miles per hour?

Answers

Answer:

4.8 hours

Step-by-step explanation:

Distance = speed × time

If Tim drove 4 hours at 60 miles per hour

Than he drove a total of 4×60 miles

He drove 240 miles

Time = distance ÷ speed

If he drove 240 miles at 50 miles per hour

Than he took 240÷50 hours

He took 4.8 hours (4 hours and 48 minutes)

A variable that is systematically linked with the factor you believe is causing the overall effect in your research is called the ________ variable. The presence of such a variable can prevent you from knowing what is really causing the effect.

Answers

Answer: Extraneous variable

Step-by-step explanation:

In an experiment , Independent variable can be manipulated by the experimenter to see the change in the dependent variable or response variable. But there are some variable known as extraneous variable that is attached to independent variable and make experimenter confuse.  

Extraneous variables is defined as :

A variable that is not intentionally involved in any study.It is systematically linked with the independent variable.It can cause effect in research.

∴ A variable that is systematically linked with the factor you believe is causing the overall effect in your research is called the extraneous variable variable. The presence of such a variable can prevent you from knowing what is really causing the effect.

There are 5 ships in a port.
1. The Greek ship leaves at six and carries coffee.
2. The ship in the middle has a black chimney.
3. The English ship leaves at nine.
4. The French ship with a blue chimney is to the left of a ship that carries coffee.
5. To the right of the ship carrying cocoa is a ship going to Marseille.
6. The Brazilian ship is heading for Manila.Next to the ship carrying rice is a ship with a green chimney.
7. A ship going to Genoa leaves at five.
8. The Spanish ship leaves at seven and is to the right of the ship going to Marseille.
9. The ship with a red chimney goes to Hamburg.Next to the ship leaving at seven is a ship with a white chimney.
10. The ship on the border carries corn.
11. The ship with a black chimney leaves at eight.
12. The ship carrying corn is anchored next to the ship carrying rice.
13. The ship to Hamburg leaves at six.
Which ship goes to Port Said? Which ship carries tea?

Answers

Answer:

The Spanish ship goes to Port Said and the French ship carries tea. However, tea can be carried by the Brazilian ship, too.

Step-by-step explanation:

French 5:00 tea blue Genoa

Greek 6:00 coffee red Hamburg

Brazilian 8:00 cocoa black Manila

English 9:00 rice white Marseille

Spanish 7:00 corn green Port Said

Derek wants to determine the height of the top of the backboard on the basketball goal at the playground. He places a standard 12-inch ruler next to the goal post and measures the shadow of the ruler and the backboard. If the ruler has a shadow of 10 inches and the backboard has a shadow of 8.5 feet, then how high is the top of the backboard?

Answers

Answer:

10.2 feet.

Step-by-step explanation:

We have been given that Derek places  a standard 12-inch ruler next to the goal post and measures the shadow of the ruler and the backboard. If the ruler has a shadow of 10 inches. We are asked t find the height of the backboard, if the backboard has a shadow of 8.5 feet.

We will use proportions to solve our given problem as ratio between sides ruler will be equal to ratio of sides of background.

[tex]\frac{\text{Actual height of ruler}}{\text{Shadow of ruler}}=\frac{\text{Actual height of backboard}}{\text{Shadow of backboard}}[/tex]

[tex]\frac{12}{10}=\frac{\text{Actual height of backboard}}{8.5}[/tex]

[tex]\frac{12}{10}*8.5=\frac{\text{Actual height of backboard}}{8.5}*8.5[/tex]

[tex]1.2*8.5=\text{Actual height of backboard}[/tex]

[tex]10.2=\text{Actual height of backboard}[/tex]

Therefore, the actual height of the back-board is 10.2 feet.

Answer:

Step-by-step explanation:

Since the backboard and the ruler are both vertical and the sun is at the same position in the sky, the triangle made by the backboard and its shadow is similar to the triangle made by the ruler and its shadow.

The ratio of the corresponding sides of the triangles are equal and the height of the backboard can be determined by solving the following proportion.

Therefore, the top of the backboard is 7.64 feet high.

Determine, in degrees, the measure of each interior angle of a regular octagon

Please show all work on how you got your answer

Answers

Answer:

Each interior angle = 135 degrees,

Step-by-step explanation:

The exterior angles of all convex polygons add up to 360 degrees.

So for a regular octagon each exterior angle = 360 / 8

= 45 degrees.

Therefore each interior angle = 180 - 45 = 135 degrees,

HELP I NEEEEED ANSWER PLEASEEEEE

Answers

Answer:

6

Step-by-step explanation:

8^2*(TS)^2=10^2

(TS)^2=36

TS=6

Answer:

Step-by-step explanation:

Triangle RST is a right angle triangle.

From the given right angle triangle,

RS represents the hypotenuse of the right angle triangle.

With m∠R as the reference angle,

RT represents the adjacent side of the right angle triangle.

ST represents the opposite side of the right angle triangle.

To determine m∠R, we would apply

the cosine trigonometric ratio.

Cos θ = adjacent side/hypotenuse. Therefore,

Cos m∠R = 8/10 = 0.8

m∠R = Cos^-1(0.8)

m∠R = 36.9 to one decimal place.

The 1985 1985 explosion at a nuclear lab sent about 1000 kilograms of a radioactive element into the atmosphere. The function f left parenthesis x right parenthesis equals 1000 left parenthesis 0.5 right parenthesis Superscript StartFraction x Over 30 EndFraction f(x)=1000(0.5) x 30 describes the​ amount, f(x), in​ kilograms, of a radioactive element remaining in the area x years after 1985 1985. If even 100 kilograms of the radioactive element remains in the​ atmosphere, the area is considered unsafe for human habitation. Find ​f( 40 40​) and determine if the area will be safe for human habitation by 2025 2025.

Answers

Answer:

Step-by-step explanation:

If I'm understanding this correctly, the rate of decay function is

[tex]f(x)=1000(.5)^{\frac{x}{30}}[/tex]

and we want to solve for the amount of element left after x = 40 years.  That would make our equation

[tex]f(40)=1000(.5)^{1.33333333333}[/tex]

Multiply the repeating decimal by .5 to get

f(40) = 1000(.3968502631)

and f(40) = 396.85

So no, it's not safe for human habitation.

Final answer:

f(40) ≈ 793.7 kilograms. The area will not be safe for human habitation by 2025.

Explanation:

For the decay, to find f(40), we substitute x=40 into the function f(x)=1000(0.5)x/30.

f(40)=1000(0.5)40/30

f(40)=1000(0.5)4/3

f(40) ≈ 1000(0.7937)

f(40) ≈ 793.7 kilograms

Since the question asks if the area will be safe for human habitation by 2025, we need to check if f(40) is less than or equal to 100 kilograms.

But the value of f(40) is about 793.7 kilograms, which is greater than 100 kilograms.

Therefore, the area will not be safe for human habitation by 2025.

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Jim's work evaluating 2 (three-fifths) cubed is shown below. 2 (three-fifths) cubed = 2 (StartFraction 3 cubed Over 5 EndFraction) = 2 (StartFraction 3 times 3 times 3 Over 5 EndFraction) = 2 (StartFraction 27 Over 5 EndFraction) = StartFraction 54 Over 5 EndFraction Which statement best describe Jim's first error? He did not multiply Three-fifths by 2 before applying the power. He did not apply the power to the denominator of Three-fifths. He did not evaluate 33 correctly. He did not multiply StartFraction 27 Over 5 EndFraction by 2 correctly.

Answers

Final answer:

Jim's first error occurred when he incorrectly applied the cube to three-fifths. He made the mistake of not applying the power to the denominator of the fraction. The answer is  54/125

Explanation:

The question revolves around a mathematical operation where Jim is attempting to determine the cube of 2 times three-fifths. Jim's first error lies in how he applied the power of three. According to the rules of exponentiation for fractions, you should apply the power to both the numerator and denominator. Hence, Jim's first mistake was that he did not apply the power to the denominator of three-fifths. Instead of merely cubing the numerator (3), Jim should have also cubed the denominator (5). He should have performed the calculation as follows:

= 2 x (3/5)^3

= 2 x (3^3/5^3)

= 2 (27/125).

= 54/125

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Jim first errored by failing to apply the exponent to both the numerator and denominator of the fraction before multiplying by two. The correct calculation for cubing a fraction should involve cubing both the numerator and the denominator, which would have resulted in 54/125 instead of 54/5.

The first error that Jim made was not applying the power to both the numerator and the denominator of the fraction before multiplying by two. When cubing a number in fractional form, such as three-fifths, one must cube both the numerator (33) and the denominator (53) to correctly apply the exponent to the entire fraction. The correct method is to first cube three-fifths, which results in 27/125, and then multiply that result by 2, leading to the final answer of 54/125, not 54/5 as Jim calculated.

It's important to follow the correct order of operations and apply exponents before multiplication. In this case, to find the value of 2 × (three-fifths) cubed, the calculation should be 2 × (3/5)3, which simplifies to 2 × (27/125), and then to 54/125.

Compare the ratios of sauce to dough. Which of the
following are true? Check all that apply.
Adrian's recipe has a greater ratio of sauce to
dough.
Juliet's recipe has a greater ratio of sauce to dough.
Adrian's and Juliet's recipes have equal ratios of
sauce to dough.
The ratios can be compared by comparing 15 to 18
because 30 is in both dough columns.

Answers

Answer:b also d

Step-by-step explanation:

Adrian's recipe has a greater ratio of sauce to dough, and the ratios can be compared by comparing 15 to 18 because 30 is in both dough columns.

In Adrian's recipe, the ratio of sauce to dough is 15:30, which simplifies to 1:2.

In Juliet's recipe, the ratio of sauce to dough is 18:30, which also simplifies to 1:2.

Since both ratios simplify to the same value of 1:2, it means that Adrian's and Juliet's recipes have equal ratios of sauce to dough.

Therefore, the statement "Adrian's and Juliet's recipes have equal ratios of sauce to dough" is true.

The reason we can compare the ratios by looking at 15 and 18 is because both of these values represent the amount of sauce, and 30 represents the amount of dough in both recipes.

By comparing the sauce portions directly, we can determine that the ratios are indeed equal.

It's important to note that the absolute values of the sauce and dough quantities are less relevant in this context than their proportions, which are expressed in the ratios.

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A​ town’s January high temperatures average 36 degrees​ (F) with a standard deviation of 10 degrees while in July the mean high temperature is 74 degrees and the standard deviation is 8. In which month is it more unusual to have a day with a high temperature of​ 55? explain

Answers

Final answer:

After calculating the z-scores for a high temperature of 55 degrees in both January and July, it was found that a temperature of 55 degrees is more unusual in July than in January due to the higher absolute value of its z-score.

Explanation:

To determine in which month it is more unusual to have a day with a high temperature of 55 degrees, we compare the standardized scores (z-scores) of 55 degrees for January and July. The z-score is calculated by subtracting the mean from the observation and then dividing the result by the standard deviation. For January, with a mean of 36 and standard deviation of 10, the z-score is (55 - 36) / 10 = 1.9. For July, with a mean of 74 and standard deviation of 8, the z-score is (55 - 74) / 8 = -2.375.

Comparing the absolute values of the z-scores, the z-score for July is higher in absolute value, indicating that a temperature of 55 degrees is more unusual in July than it is in January.

Which of the following has a finite solution for a three-variable system of equations?

A. three planes intersecting at a point
B. three planes intersecting at a line
C. three parallel planes
D. two parallel planes

Answers

Answer:

A. three planes intersecting at a point

Step-by-step explanation:

Whenever three planes intersect at a point, then we have an ordered triplet (x,y,z) that is a solution to the associated system of equation.

This is a unique solution and it is finite.

However three planes intersecting at a line gives infinitely many solutions.

Three or two parallel planes may have no solution or or infinitely many solutions when they coincide.

The perimeters of two 30-60-90 triangles are in the ratio 1:2. If the length of the hypotenuse of the larger triangle is 20 cm, find the length of the longer leg of the smaller triangle.

Answers

Answer:

The answer to your question is 5[tex]\sqrt{3}[/tex]

Step-by-step explanation:

Data

Proportion 1:2

Hypotenuse of the larger triangle = 20

length of the longer leg of the smaller triangle = ?

Process

1.- Remember the proportions of a 30- 60 - 90 triangle

hypotenuse = 2x

short leg = x

long leg = x[tex]\sqrt{3}[/tex]

2.- Use the previous information to find the lengths of the larger triangle

hypotenuse = 20 = 2x

short leg = x = 10

large leg = 10[tex]\sqrt{3}[/tex]

3.- Use the previous information to find the lengths of the smaller triangle

Proportion 1:2

hypotenuse = 10

short leg = x = 5

long leg = 5[tex]\sqrt{3}[/tex]

Answer:

It’s 5 radical 3

Step-by-step explanation:

Resorts-R-Us charges $ 125 a night to rent a suite. If you purchase their oneyear membership fee for $350, you only pay $75 a night. Which is a better deal?

Answers

Answer:

Step-by-step explanation:

Let x represent the number of nights for which you rent a suite.

Resorts-R-Us charges $ 125 a night to rent a suite. If you choose this plan, the total cost of renting the suite for x nights would be

125 × x = 125x

If you purchase their one year membership fee for $350, you only pay $75 a night. This means that the total cost of renting a suite for x nights would be

75x + 350

For the plan involving membership to be a better deal,

75x + 350 < 125x

350 < 125x - 75x

350 < 50x

50x > 350

x > 350/50

x > 7

After 7 nights, the membership option would be a better deal. If you intend to rent the suite for lesser than 7 nights in a year, then the first option is a better deal.

What is the value of n?

Enter your answer in the box.
n =
m
Circle with two intersecting chords forming an x shape in the circle. The top left side of the x shape is labeled 5 meters. The top right side of the x shape is labeled 2 meters. The bottom left side of the x is labeled 15 meters.The bottom right side of the x is labeled n.

Answers

Answer:

6 meters

Step-by-step explanation:

Intersecting Chord Theorem: When two chords intersect each other inside a circle, the products of their segments are equal.

One chord is divided into two segments with lengths of 15 m and 2 m.

Anothe chord is divided into two segments with measures of 5 m and n m.

Therefore,

[tex]5\cdot n=15\cdot 2\\ \\5n=30\\ \\n=6\ m[/tex]

Answer:

6 m

Step-by-step explanation:

just took the test

Dan's business loses $9 each day. Which equation would be used to show how much money Dan's business has lost in a week? A. -9 × 7 B.-9 × (-7) C.9 × 7 D.9 × (-7)

Answers

Answer:

[tex]C. \: 9 \times 7[/tex]

NASA is sending a probe to Alpha Centauri and then to Sirius. A problem with the probe is noticed while it is at Alpha Centauri, so it must go back to Erth before going to Sirius. Alpha Centauri is 4.3 light-years away from Earth and Sirius is 8.6 light-years away. The probe is traveling at 18.03 km/s, there are 1.58125 x 10-5 light-years in one astronomical unit. How long will the probe have been traveling from when it first leaves Earth to when it arrives at Sirius?

Answers

Answer:

Time = 9.0252 *10^12 s

Step-by-step explanation:

Given:

- The distance from Earth to Alpha Centauri = 4.3 light years

- The distance from Earth to Sirius = 8.6 light years

- Speed of the probe is V = 18.03 km/s

- 1 AU = 1.58125 x 10-5 light-years

Find:

How long will the probe have been traveling from when it first leaves Earth to when it arrives at Sirius?

Solution:

- We will track probe for each destination it reaches one by one:

                       Earth ------> Alpha Centauri d_1 = 4.3 light years

                       Alpha Centauri ------> Earth d_2 =4.3 light years

                       Earth ------> Sirius                  d_3 = 8.6 light years  

                       Total distance                       D    = 17.2 light years.

- Now we know the total distance traveled by the probe is D. We will convert the distance into km SI units:

                          1 AU    ------------------> 1.58125 x 10-5 light-years

                          x AU   ------------------> 17.2 light years.

- Using direct proportions

                           x = 17.2 / (1.58125 x 10-5) = 1087747.036 AU

Also,

                          1 AU  ---------------------> 149597870700 m

                           1087747.036 AU  ---->    D m

- Using direct proportions

                            D =   1087747.036*149597870700  = 1.62725*10^17 m

- Now use the speed - distance - time formula to compute the total time taken:

                            Time = Distance traveled (D) / V

                            Time = 1.62725*10^17 / 18.03*10^3    

Answer:               Time = 9.0252 *10^12 s

What is the sum of the linear expression 3x + 9 and 2x + 4

Answers

Answer:

5x + 13

Step-by-step explanation:

(3x + 9 ) + (2x + 4)

It's quite simple, we just have to add the parts that have x to each other and those that don't have x to each other

3x + 2x + 9 +4 =

then the result is

5x + 13

A 13 foot ladder is leaning against a wall. The distance from the top of the ladder to the bottom of wall is 7 ft more than the distance from the bottom of the ladder to the wall. Find the distance from the bottom of the ladder to the wall.

Answers

Final answer:

Using the Pythagorean theorem, the distance from the bottom of the ladder to the wall is found to be 5 ft, after solving the quadratic equation that arises from the conditions given.

Explanation:

The question asks for the distance from the bottom of the ladder to the wall when a ladder is leaning against it. We can use the Pythagorean theorem to solve this problem as it forms a right-angled triangle. Let's denote the distance from the bottom of the ladder to the wall as x, then the distance from the top of the ladder to the bottom of the wall would be x + 7 ft. Since the ladder's length, which represents the hypotenuse, is 13 ft, we can set up the equation:

x2 + (x + 7)2 = 132

Expanding this, we get:

x2 + x2 + 14x + 49 = 169

Combining like terms:

2x2 + 14x - 120 = 0

Dividing everything by 2 to simplify:

x2 + 7x - 60 = 0

Factoring the quadratic equation:

(x + 12)(x - 5) = 0

The possible values for x are -12 and 5. Since distance cannot be negative, the distance from the bottom of the ladder to the wall is 5 ft.

The Quick Change Oil Company has a number of outlets in the metropolitan Seattle area. The numbers of oil changes at the Oak Street outlet in the past 20 days are:
65 98 55 62 79 59 51 90 72 56
70 62 66 80 94 79 63 73 71 85
The data are to be organized into a frequency distribution.
How many classes would you recommend?
What class interval would you suggest?
What lower limit would you recommend for the first class?
Organize the number of oil changes into a frequency distribution.
Comment on the shape of the frequency distribution. Also determine the relative frequency distribution.

Answers

Final answer:

The recommended number of classes is 5, and the class interval is 10. The first class's lower limit would be 50. To create a relative frequency distribution, divide each class frequency by the total

Explanation:

First, we have to calculate the range of the data by subtracting the smallest number from the highest number (98-51 = 47). A typical choice for the number of classes might be between five and 20. The

square root rule

suggests a round number near the square root of the number of observations, which is approx 4.47 in this case; you can round to 5. Now we divide the range by the number of classes (47/5 approximately 9). So, the class interval would be 10 (we round up as it does not make sense to have a fraction of an oil change). If the smallest number is 51, the lower limit for the first class would be 50. Hence, the

frequency distribution

would break down like this: 50-59, 60-69, 70-79, 80-89, 90-99. To create a relative frequency distribution, divide each class frequency by the total number of observations and multiply by 100 to convert to percentages. As for the shape, you would need to plot the data to see, but it may have a normal distribution as service levels often do.

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Looking into the sky one night, Tori wondered how far into outer space she would get if she drove a car for 3.21 × 103 hours at a rate of 70mph. She calculated and determined that a car travelling at 70 mph covers approximately 1.13 × 105 meters per hour. Tori wrote this expression to determine the distance she would travel into outer space. (3.21 × 103)(1.13 × 105) Estimate the distance travelled

Answers

Answer:

         [tex]\large\boxed{\large\boxed{3\times 10^8meters}}[/tex]

Explanation:

One of the applications of scientific notation is to make estimations rounding the whole part of the numbers, i.e. the digits before the decimal point, to the nearest integer, and adding the exponents of the powers of base 10.

Here, you must estimate this product of two numbers written is scientific notation:

          [tex](3.21\times 10^3)(1.13\times 10^5)[/tex]

Then, for an estimation you round 3.21 to 3 and 1.13 to 1, then multiply 3 × 1 = 3. That will be the coefficient of your new power of 10.

The power or exponent will be the sum of the powers of the numbers that are being multiplied, i.e. 3 + 5 = 8.

And the result is [tex]3\times 10^8[/tex]

The unit is meters, so you write your answer as: [tex]3\times 10^8meters[/tex]

Answer:

b. 3*10^8

Step-by-step explanation:

Combine like terms in the expression. 3r + r *​

Answers

Answer:

4r

Step-by-step explanation:

If you take away the variable, add the 3 and metaphorical 1

3 + 1 = 4

Adding like terms (3+1) and then putting the variable back in makes 4r

Hope this helps, mark brainliest

Answer:

4r

Step-by-step explanation:

3r + r = 4r

I hope this helps!

Write the sum using summation notation, assuming the suggested pattern continues. 5 - 15 + 45 - 135 + ...

summation of five times three to the power of the quantity n plus one from n equals zero to infinity
summation of five times negative three to the power of n from n equals zero to infinity
summation of five times three to the power of n from n equals zero to infinity
summation of five times negative three to the power of the quantity n plus one from n equals zero to infinity

Answers

Answer:

summation of five times negative three to the power of n from n equals zero to infinity

Step-by-step explanation:

Summation Notation

It represents the sum of a finite or infinite number of terms. Let's analyze the terms of the given succession:

5-15+45-135+...

If we take 5 as a common factor, we have

5(1-3+9-27+...)

The parentheses contain the alternate sum/subtraction of powers of 3. The odd terms are positive, the even terms are negative, thus the exponent must be n starting from 0 or n-1 starting from 1

The summation is then represented by

[tex]\sum_{n=0}^{\infty}5(-3)^n[/tex]

This corresponds with the option:

summation of five times negative three to the power of n from n equals zero to infinity

Final answer:

The correct summation notation for the series 5 - 15 + 45 - 135 + ... is the summation of five times negative three to the power of n from n equals zero to infinity.

Explanation:

The given sequence is 5 - 15 + 45 - 135 + ... which can be seen as a geometric series with a pattern of alternating signs and a common ratio of -3. The first term of the sequence is 5 (when n=0), and each subsequent term is multiplied by -3. Therefore, to write this pattern using summation notation, the nth term can be represented as 5 × (-3)^n. So, the summation notation for the entirety of the series from n equals 0 to infinity is:

Σ [5 × (-3)^n], from n = 0 to infinity

This matches the option: summation of five times negative three to the power of n from n equals zero to infinity.

A company wants to determine the amount of a vitamin mix that can be enclosed in a capsule like the one shown. The capsule has a radius of 3millimeters (mm) and a length of 10 mm. How much vitamin mix is needed?

Answers

Answer:

226.08 mm³

Step-by-step explanation:

The figure below shows a capsule mad of;

Two hemisphere and an open cylinder

To determine the amount of vitamin that can be enclosed in the capsule, we determine the volume of the capsule;

First we determine the volume of the two hemisphere;

Volume of a hemisphere = 2/3 πr³

Therefore; Taking π to be 3.14

Then;

Volume of the hemisphere = 2/3 × 3.14 × 3³

                                             = 56.52 mm³

But, since there are two equal hemispheres;

Then;

Volume of hemispheres = 56.52 mm³ × 2

                                        = 113.04 mm³

Second we determine the volume of the cylinder

Volume of the cylinder is given by;

Volume = πr²h

Height = (10 mm - (2× 3mm)

           = 4 mm

Thus, taking π to be 3.14

Then;

Volume of the cylinder = 3.14 × 3² × 4

                                      = 113.04 mm³

Thus, Volume of the capsule = 113.04 mm³ + 113.04 mm³

                                                = 226.08 mm³

PLEASE HELP ASAP!!! I NEED CORRECT ANSWERS ONLY PLEASE!!!

Find m∠R.

Write your answer as an integer or as a decimal rounded to the nearest tenth.


m∠R = °

Answers

Answer:

Therefore,

[tex]m\angle R = 69.4\°[/tex]

Step-by-step explanation:

Given:

In Right Angle Triangle PQR at ∠Q = 90° such that

RQ = 3     ....Adjacent side of angle R

PQ = 8     ....Opposite side of angle R

To Find:

m∠R = ?

Solution:

In Right Angle Triangle PQR, Tan Identity,

[tex]\tan R= \dfrac{\textrm{side opposite to angle R}}{\textrm{side adjacent to angle R}}[/tex]

Substituting the values we get

[tex]\tan R= \dfrac{PQ}{QR}=\dfrac{8}{3}=2.6666\\\\\angle R=\tan^{-1}(2.666)=69.439=69.4\°[/tex]

Therefore,

[tex]m\angle R = 69.4\°[/tex]

Sam eats 1/2 of a chocolate bar. Jack eats 1/4 of the remaining chocolate bar. After both Jack and Sam eat their portions of the chocolate bar how much is left uneaten of the original whole chocolate bar?

Answers

Final answer:

After Sam eats 1/2 and Jack eats 1/4 of the remaining chocolate bar, 3/8 of the original chocolate bar is left uneaten.

Explanation:

Sam eats 1/2 of a chocolate bar. Jack then eats 1/4 of the remaining chocolate bar. To determine how much of the chocolate bar is left, we need to perform a couple of simple calculations. After Sam eats his portion, 1/2 of the bar is left. Jack eats 1/4 of what remains after Sam, which is 1/4 of 1/2, or 1/2 * 1/4 = 1/8 of the original bar.

This means that Jack's portion is 1/8 of the entire chocolate bar. Now, the total amount eaten by Sam and Jack together is 1/2 (Sam's portion) + 1/8 (Jack's portion). To add these fractions, they need to have a common denominator, which in this case is 8. This makes Sam's portion 4/8 when expressed with the common denominator. Now, add 4/8 (Sam's adjusted portion) + 1/8 (Jack's portion) = 5/8.

Therefore, the total amount eaten by both is 5/8 of the bar, leaving 3/8 of the original chocolate bar uneaten.

Pratap puri Row 22 miles down a river in two hours but the return trip took him 5 1/2 hours find the rate pratap Control in Stillwater and find the rate of the current X equal rate pratap can row in still water and y equals rate of the current

Answers

Answer:

x= 7.5 mile/h

y= 3.5 miles / h

Step-by-step explanation:

Given x and y

so, x+y = speed down river

and x-y= speed up river

using

travel time = distance / speed for each case;

we get;

22/x+y=2  ---(1)

and

22/x-y=5.5 -----(2)

Solving equations simultaneously

eq 1 gives

2x+2y=22  ---(3)

eq 2 gives

5.5x-5.5y=22 ----(4)

Multiply eq 3 by 2.75

==> 5.5x+5.5y=60.5 --- (5)

adding eq 4 with eq 5

==> 11x =82.5

==> x= 7.5 miles/h

put this value in eq 3

==> 2(7.5)+2y=22

==> 2y=22-19.8

==> 2y=7

==> y = 3.5

Final answer:

Once setting up two equations based on downstream and upstream velocities, using variables x for Pratap's rowing speed and y for the current's speed, you can solve for these variables. The results show Pratap can row at a speed of 7.5 mph in still water, while the rate of the current is 3.5 mph.

Explanation:

Firstly, we have to understand that Pratap's speed with the current and against the current will be affected. Let's say x is the speed of Pratap rowing in still water, and y is the speed of the current. When going downstream (in the direction of the current), Pratap's speed is (x + y) since the current helps him. He covered a distance of 22 miles in 2 hours, so the rate (velocity) can be found by dividing distance by time. Hence, x + y = 22/2 = 11 miles per hour.

On the other hand, when rowing upstream (against the current), Pratap's speed is (x - y), because now the current hinders his rate. He covered the same distance in 5 1/2 hours, so x - y = 22/(5.5) = 4 miles per hour.

Now, we have two equations: x + y = 11 and x - y = 4. Solving these equations (by adding them), we find that 2x = 15 hence x = 7.5. Pratap can row in still water at a speed of 7.5 miles per hour. Substituting x=7.5 into either of the original equations we get y = 3.5. Hence, the rate of the current is 3.5 miles per hour.

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A baby otter was born 3/4 of a month early at first it's weight was 7/8 kg which is 9/10 kg less than the average weight of newborn otter in the aquarium what is the average weight of a newborn otter

Answers

Answer:

The average weight of the newborn otter is  [tex]\frac{71}{40}\ kg.[/tex]

Step-by-step explanation:

Given:

A baby otter was born 3/4 of a month early at first it's weight was 7/8 kg which is 9/10 kg less than the average weight of newborn otter in the aquarium.

Now, to find the average weight of the newborn otter.

Let the average weight of the newborn otter be [tex]x.[/tex]

It's weight was = [tex]\frac{7}{8} \ kg.[/tex]

It's weight is less than the average weight of newborn by = [tex]\frac{9}{10} \ kg.[/tex]

According to question:

[tex]x-\frac{9}{10}=\frac{7}{8}[/tex]

Adding both sides by [tex]\frac{9}{10}[/tex] we get:

[tex]x=\frac{9}{10} +\frac{7}{8}[/tex]

[tex]x=\frac{36+35}{40}[/tex]

[tex]x=\frac{71}{40} \ kg.[/tex]

Therefore, the average weight of the newborn otter is [tex]\frac{71}{40}\ kg.[/tex]

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