A wheelchair ramp is to be built from ground level to a platform that is 9 feet above the ground. The angle that the ramp makes with the ground is 11 degrees. What is the length of the ramp?

Answer:

D) 8 inches

Step-by-step explanation:

Since the ratio is 2:60 inches, therefore the model should be:

2/60 X 240=8 inches tall, or 8/12=2/3 foot tall.

Answer:

Triangle DEF is not a right triangle ; possible lengths are 20 & 15

Step-by-step explanation:

For right triangle;

the sum of the square of the two adjacent sides must equal the square of the hypotenus.

Therefore, (6^2)+(11^2)≠(13^2).

the possible length are 20 & 15 because

(20^2)+(15^2)=(25^2)

Triangle DEF with sides lengths of 6, 11, and 13 units is not a right triangle as the Pythagorean theorem is not satisfied. To find the lengths of the legs of a right triangle with a hypotenuse of 25, one can use the Pythagorean theorem to find whole number pairs that satisfy the equation.

To determine whether triangle DEF is a right triangle with sides of lengths 6, 11, and 13 units, we can use the Pythagorean theorem. This theorem states that in a right triangle, the square of the length of the hypotenuse (c) is equal to the sum of the squares of the lengths of the other two sides (a and b): a² + b² = c².

Let's check if the sides of triangle DEF satisfy this condition:

Since 157 does not equal 169, triangle DEF is not a right triangle.

For the second part of the question, we are given that a right triangle has a hypotenuse with a length of 25 units and we need to find the lengths of the legs which are whole numbers. We can use the Pythagorean theorem to find pairs of integers (a and b) that satisfy the equation a² + b² = 25² = 625. Some possible pairs of legs that meet this criterion include (7, 24), (15, 20), and (9, 24). Note that there are multiple correct answers to this question.

Answer: Let the Number of hours Enzo sleeps on average per day while School is in session be Y

Y = SS/115% = SS/1.15

Step-by-step explanation:

Given in the question:

- While on vacation, Enzo sleeps 115% as much as he sleeps when school is in session.

- Enzo sleeps SS hours per day during vacation

Mathematically, SS = 115% of Y

SS = 115% × Y

115% × Y = SS

Y = SS/115%

But 115% = 115/100 = 1.15

Therefore,

Y = SS/1.15

Solved!

Answer:

option 1

Step-by-step explanation:

first we have to find the slopes of the lines

D(1, -2)     E(3, 4)

y = m*x + b

m1: slope

m1 = (y2-y1) / (x2-x1)

m1 = (4 - (-2)) / (3 - 1)

m1 = 4+2 / 3-1

m1 = 6 / 2

m1 = 3

we do the same with the other 2 points

D(-1, 2)     E(4, 0)

y = m*x + b

m2: slope

m2 = (y2-y1) / (x2-x1)

m2 = (0 - 2) / (4 - (-1))

m2 = -2 / 4 + 1

m2 = -2 / 5

m1 = 3        m2 = -2/5

for 2 lines to be perpendicular it must be met

m1 * m2 = -1

we check if they are perpendicular

3 * -2/5 = -1

-6/5 = -1   <-- no perpendicular

Answer:

C. [tex]-0.00005d^2+11.8d-9000[/tex]

Step-by-step explanation:

Given:

Cost Price for producing 'd' dog lashes = [tex]9000+3.2d[/tex]

Revenue Generated from selling 'd' dog lashes = [tex]d(15-0.00005d)[/tex]

We need to find the profit earned from producing and selling 'd' dog lashes.

Solution:

Now we know that;

profit earned from producing and selling 'd' dog lashes can be calculated by Subtracting Cost Price for producing 'd' dog lashes from Revenue Generated from selling 'd' dog lashes.

framing in equation form we get;

Profit earned = [tex]d(15-0.00005d)-(9000+3.2d)[/tex]

Now Applying Distributive property we get;

Profit earned = [tex]15d-0.00005d^2-9000-3.2d[/tex]

Now Combining like terms we get;

Profit earned = [tex]-0.00005d^2+15d-3.2d-9000[/tex]

Profit earned = [tex]-0.00005d^2+11.8d-9000[/tex]

Hence  Profit earned from producing and selling 'd' dog lashes is [tex]-0.00005d^2+11.8d-9000[/tex].

Final answer:

The polynomial representing the profit from producing and selling d dog leashes is -0.00005d² + 11.8d - 9000, calculated by subtracting the cost (9000 + 3.2d) from the revenue (d(15 - 0.00005d)).

Explanation:

The student's question relates to finding the polynomial expression that represents the profit earned from producing and selling d dog leashes. Profit is calculated by subtracting the cost from the revenue. The cost polynomial is given as 9000 + 3.2d, and the revenue polynomial is d(15 - 0.00005d).

To find the profit, we subtract the cost from the revenue:

Profit = Revenue - Cost

Profit = (d(15 - 0.00005d)) - (9000 + 3.2d)

Profit = 15d - 0.00005d² - 9000 - 3.2d

Profit = -0.00005d² + (15 - 3.2)d - 9000

Profit = -0.00005d² + 11.8d - 9000

Therefore, the correct polynomial that represents the profit is -0.00005d² + 11.8d - 9000.

Answer:

5 inches

Step-by-step explanation:

See attachment for explanation.

Answer:

x = 0 or -4

Step-by-step explanation:

x² + 4x = 0

To complete the square, take half of the middle coefficient, square it, then add to both sides.

(4/2)² = 2² = 4

x² + 4x + 4 = 4

(x + 2)² = 4

x + 2 = ±2

x = -2 ± 2

x = 0 or -4

Answer: He makes 23 pints this year .

Step-by-step explanation:

Given : Oliver makes blueberry jam every year the number of pints of jam he makes this can be represented by the expression

[tex]4p - 9[/tex] , where  p = the number of pints of jam he made last year.

if Oliver made 8 pints of jam last year , then p = 8

Substitute value p= 8 in the given expression  , we get

Then, the number of  pints he make this year = [tex]4(8)-9 = 32-9=23[/tex]

Hence, the number of pints Oliver make this year = 23

Two pounds of gummy bears will cost $2.67. The unit rate for each pounds of gummy bears is measured in dollars.

Word problems in mathematics involve the use of mathematical concepts and arithmetic operations to solve real-life cases. It involves a careful understanding of the problem you want to solve.

From the parameters given:

By cross multiplying, we have:

[tex]\mathbf{x = \dfrac{2 \ pounds \times \$4.00}{\$3.00}}[/tex]

x = $2.67

Learn more about word problems in mathematics here:

https://brainly.com/question/21405634

Final answer:

The cost for two pounds of gummy bunnies is $2.66, with the unit rate being $1.33 per pound after rounding to two decimal places.

Explanation:

To determine how much two pounds of gummy bunnies will cost at Joan's candy emporium, we first need to calculate the unit rate of the gummy bunnies that are selling for $4.00 per three pounds. The unit rate is found by dividing the total cost by the number of pounds:

Unit Rate = Total Cost / Number of Pounds

Unit Rate = $4.00 / 3 pounds = $1.33 per pound (rounded to two decimal places)

Now that we have the unit rate, we can determine the cost for two pounds of gummy bunnies:

Cost for Two Pounds = Unit Rate x Number of Pounds

Cost for Two Pounds = $1.33 per pound x 2 pounds = $2.66 (rounded to two decimal places)

Answer:

The answer is c. 8 hours

Step-by-step explanation:

Since her battery dropped 25% in 2 hours then for it to drop 100% would take 8 hours.

25%+25%+25%+25%= 100%

so with this logic

25%= 2 hours

2+2+2+2=8

Hoped this helped !

Cheers, Z

Zoey can expect 8 hours of use from her iPad on a full battery charge (c).

To find the total hours Zoey can expect from her iPad on a full battery charge, we need to determine how many hours the battery percentage dropped for each hour of use.

If the battery dropped by 25% in 2 hours, that means it dropped by 12.5% (25% divided by 2) per hour.

To find the total hours, we divide 100% (full battery charge) by the percentage dropped per hour. In this case, 100% divided by 12.5% equals 8 hours.

Therefore, Zoey can expect 8 hours(c) of use from her iPad on a full battery charge.

https://brainly.com/question/35390557

#SPJ3

Answer:

The height of the building is 153.664 meter.

Step-by-step explanation:

Consider the provided function.

[tex]s(t) = 4.9t^2 + v_0 t + s_0[/tex]

Here t represents the time v₀ represents the initial velocity, s₀ represents the initial height and s(t) represents the height after t seconds.

It is given that the splash is seen 5.6 seconds after the stone is dropped.

That means after 5.6 seconds height s(t) = 0, Also the initial velocity of the stone is 0.

Substitute respective values in the above function.

[tex]0 = 4.9(5.6)^2 +5.6(0)+ s_0[/tex]

[tex]0 = 4.9(31.36)+ s_0[/tex]

[tex]s_0=-153.664[/tex]

As height can't be a negative number so the value of s₀ is 153.664.

Hence, the height of the building is 153.664 meter.

Answer:

The submarine will be located 1350ft below sea level or (-1350ft)

Step-by-step explanation:

First we must find the distance traveled

[tex](\frac{300}{1} )(\frac{4.5}{1})[/tex]

From this, we are able to calculate that traveled distance of the submarine.

300 x 4.5 = 1350

1350 + 0 (sea level) = 1350

Therefore the distance traveled by the submarine is 1350ft

Answer:

-1350 ft

Step-by-step explanation:

Answer:

8

Step-by-step explanation:

Hi,

When we divide 5655 by N, we get remainder of 11, which means that 5655-11 is a multiple of N.

5655 - 11 = 5644 is a multiple of N.

Similarly, 5879-14 should be a multiple of N.

5879 - 14 = 5865 is a multiple of N.

Because 5644 and 5865 are both multiples of N, their difference must be a multiple of N.

5865 − 5644 = 221 then 221 is a multiple of N.

We have three number of which N can be a multiple of, however we choose to factorize the smallest possible number amongst these three, which is 221. (This is only for simplification of the solution, smaller the number, less the factors)

221 : 1, 13, 17, 221.

There are only two two - digit factors: 13 and 17.

We divide 5865 and 5644 by both numbers.

[tex]\frac{5865}{13} = 451.15 \\\frac{5865}{17} = 345 \\\frac{5644}{13} = 434.15 \\\frac{5644}{17} = 332\\[/tex]

Looking at these results, we know only 17 divides all three numbers.

Hence N=17.

The sum of both digits will be: 1 + 7 = 8

Subtract the two given numbers excluding their identical remainders to find a multiple of the divisor N. By then finding a two-digit factor of this multiple that can divide both numbers, we get N = 28. The sum of its digits is 10.

When a number is divided by a divisor and leaves the same remainder, the difference between these numbers is a multiple of that divisor. Therefore, as given, when 5655 is divided by a positive two-digit integer N, the remainder is 11, and also when 5879 is divided by N, the remainder is 11. To find N, we subtract the two numbers before considering the remainder, which will give us a number that is a multiple of N: 5879 - 5655 = 224.

So, N divides 224 perfectly. The factors of 224 that are two-digit numbers are 14, 16, and 28. However, since the remainder when dividing both 5655 and 5879 by N is identical and equal to 11, we need to make sure that both 5655-11 and 5879-11 are divisible by N equally, thus 5644 and 5868 should be divisible by N. The correct N which fulfills this condition is 28.

The sum of the digits of N or 28 is: 2 + 8 = 10.

Answer:

calculator that what I got 56

Step-by-step explanation:

Answer:

  86 °F = 30 °C

Step-by-step explanation:

Put the given number in the equation and solve for C.

  86 = 9/5C +32

  54 = 9/5C

  (5/9)54 = C = 30

The equivalent is 30 degrees Celsius.

Final answer:

To convert 86 degrees Fahrenheit to Celsius, use the formula T°C = 5/9 (86 - 32). Subtracting 32 from 86 and then multiplying by 5/9 gives a result of 30 degrees Celsius.

Explanation:

The question asks how to find the Celsius equivalent of 86 degrees Fahrenheit using the formula to convert degrees Fahrenheit to degrees Celsius. The formula is T°C = 5/9 (T°F - 32), where T°C is the temperature in degrees Celsius and T°F is the temperature in degrees Fahrenheit.

To convert 86°F to Celsius, substitute 86 for T°F in the formula:

T°C = 5/9 (86 - 32)

First, subtract 32 from 86, which gives 54. Then, multiply 54 by 5/9 to get the final result:

T°C = 5/9 × 54

T°C = 30

Therefore, 86 degrees Fahrenheit is equivalent to 30 degrees Celsius.

Answer:

x=16

Step-by-step explanation:

Since triangle DGH is parallel to trianle DBN, the corresponding sides are also proportional.

We have [tex]\frac{DN}{DH}=\frac{DB}{DG}[/tex]

This implies that:

[tex]\frac{40}{40+x}=\frac{30}{42}[/tex]

We cross multiply to get;

[tex]30(40+x)=42*40[/tex]

This implies that:

[tex](x+40)=14*4[/tex]

[tex]x+40=56[/tex]

[tex]x=56-40[/tex]

[tex]x=16[/tex]

Answer:

Attached is the image of the solution . cheers

Combining 2s and −4s gives an equivalent expression of −2s.

We need to combine the like terms. Like terms are terms that have the same variable raised to the same power. In this case, both terms involve the variable "s."

In the expression 2s + (−4s), both terms are like terms because they both contain the variable "s." The coefficients are 2 and −4.

To combine like terms, you simply add or subtract their coefficients while keeping the variable the same:

Coefficient of the first term: 2

Coefficient of the second term: −4

Now, perform the arithmetic operation:

2 + (−4) = −2

Answer: b. 70%

Step-by-step explanation:

Given : Nik logs the following hours meeting with clients (c) or doing other work (o) :

Mon: 6 c, 4 o

Tue: 8 c, 2 o

Wed: 9 c, 1 o

Thu: 7 c, 3 o

Fri: Off

The number of hours Nik spend with clients on Thursday = 7 [Number of corresponding to c is 7 in the table]

Total hours he spend in work on Thursday =  7+3 = 10

The percent of time Nik spent with clients on Thursday :

[tex]\dfrac{\text{Number of hours he spent with clients}}{\text{Total works he work on Thursday}}\times100\\\\=\dfrac{7}{10}\times100=7\times10\%=70\%[/tex]

Hence, the Nik spent 70% of his time with clients on Thursday.

Thus , the correct option is b. 70%.

Answer:

Step-by-step explanation:

Triangle WXY is a right angle triangle.

From the given right angle triangle,

WX represents the hypotenuse of the right angle triangle.

With m∠W as the reference angle,

WY represents the adjacent side of the right angle triangle.

XY represents the opposite side of the right angle triangle.

To determine m∠W, we would apply

the cosine trigonometric ratio.

Cos θ = adjacent side/hypotenuse. Therefore,

Cos W = 5/7 = 0.7143

W = Cos^-1(0.7143)

W = 44.1° to the nearest tenth.

Answer:

The probability that Meena wins is 21/25

Step-by-step explanation:

In order for Meena to win, she needs to win the next turn or the following one, otherwise, she loses. The probability for that is equal to substract from 1 the probability of the complementary event: bob wins in the next 2 turns. Since each turn is independent from the other, we can obtain the probability of Bob winning the next 2 turns by taking the square of the probability of him winning on one turn, hence it is

[tex] {\frac{2}{5}}^2 = \frac{4}{25} [/tex]

Thus, the probability for Meena to win is 1-4/25 = 21/25.

Meena only needs one more point to win, and with a ⅘ or 60% probability in her favor for the next turn, she will win the game.

The question asks for the probability that Meena will win a game where she is currently ahead 9 to 6, and the game is won by the first person to reach 10 points. In each turn, there is a ⅗ chance that Bob will get 2 points and Meena will lose 1 point, and a ⅘ chance that Meena will get 2 points and Bob will lose 1 point.

To find the probability of Meena winning, we only need to look at the next round because Meena is already at 9 points and she needs only 1 point to win. Two scenarios can occur:

Bob gets 2 points, and Meena loses 1 point. This outcome is not possible because Meena cannot have 8 points; she's already at 9 points. So, this situation doesn't count.

Meena gets 2 points (which will put her at or above 10 points) and Bob loses 1 point. This is the winning scenario for Meena. The probability of this happening is ⅘ or 0.6 (since only this outcome will end the game with Meena as the winner).

Therefore, the probability that Meena will win on the next turn (and win the game) is 0.6 or 60%

Answer:

1. 3.767

2. 0.145

Step-by-step explanation:

Let X be the exam scores and Y be the number of drinks.

X     Y   X-Xbar    Y-Ybar   (X-Xbar)(Y-Ybar)    (X-Xbar)²       (Y-Ybar)²    

75    5    -2.3          2.3          -5.29                      5.29              5.29

92    3     14.7         0.3           4.41                       216.09           0.09

84    2     6.7         -0.7           -4.69                     44.89             0.49

64    4     -13.3        1.3           -17.29                     176.89           1.69

64    2     -13.3       -0.7           9.31                       176.89           0.49

86    7     8.7           4.3           37.41                     75.69            18.49

81     3     3.7           0.3           1.11                         13.69             0.09

61     0    -16.3        -2.7           44.01                     265.69          7.29

73    1      -4.3         -1.7            7.31                        18.49             2.89

93    0    15.7         -2.7           -42.39                    246.49          7.29

sumx=773, sumy=27, sum(x-xbar)(y-ybar)= 33.9 , sum(X-Xbar)²= 1240.1 ,sum(Y-Ybar)²= 44.1

Xbar=sumx/n=773/10=77.3

Ybar=sumy/n=27/10=2.7

1.

[tex]Cov(x,y)=sxy=\frac{Sum(X-Xbar)(Y-Ybar)}{n-1}[/tex]

Cov(x,y)=33.9/9

Cov(x,y)=3.76667

The the sample co-variance between the exam scores and the number of energy drinks consumed is 3.767

2.

[tex]Cor(x,y)=r=\frac{Sum(X-Xbar)(Y-Ybar)}{\sqrt{Sum(X-Xbar)^2sum(Y-Ybar)^2} }[/tex]

[tex]Cor(x,y)=r=\frac{33.9}{\sqrt{(1240.1)(44.1)} }[/tex]

Cor(x,y)=r=33.9/233.85553

Cor(x,y)=r=0.14496

The sample correlation coefficient between the exam scores and the number of energy drinks consumed 0.145.

Calculate sample covariance and correlation coefficient between exam scores and energy drinks consumed by students.

Sample Covariance:
1. Calculate the mean of exam scores (77.3) and number of drinks (2.7).
2. Subtract the mean from each score and drink value to get the deviations.
3. Multiply the deviations of exam scores and drinks for each student, sum them up, and divide by 10 to get the sample covariance of approximately -22.6.

Sample Correlation Coefficient:
1. Calculate the standard deviations of exam scores (12.15) and number of drinks (2.51).
2. Divide the sample covariance by the product of the standard deviations to get the correlation coefficient of around -0.79.

Answer: [tex](x+6)^{2}+(y+5)^{2}=r^{2}[/tex]

Step-by-step explanation:

The formula for finding the equation of circle with center (a,b) is given as :

[tex](x-a)^{2}+(y-b)^{2}=r^{2}[/tex]

The end point of the diameter is given as :

(-10, -6) and (-2, -4) , this means that the coordinate of the center is the Mid -point of the end point .

The mid - point = ( -6 , - 5)

substituting into the formula , we have

[tex](x-(-6))^{2}+(y-(-5))^{2}[/tex][tex]= r^{2}[/tex]

[tex](x+6)^{2}+(y+5)^{2}=r^{2}[/tex]

This is the equation of the circle

Answer: y = 3x - 5

Step-by-step explanation:

The equation of a straight line can be represented in the slope intercept form as

y = mx + c

Where

c = intercept

m = slope = (change in the value of y in the y axis) / (change in the value of x in the x axis)

The equation of the given line is

y = -1/3x + 2

Comparing with the slope intercept form, slope = - 1/3

If two lines are perpendicular, it means that the slope of one line is the negative reciprocal of the slope of the other line. Therefore, the slope of the line passing through

(2, 1) is 3/1 = 3

To determine the intercept, we would substitute m = 3, x = 2 and y = 1 into y = mx + c. It becomes

1 = 3 × 2 + c = 6 + c

c = 1 - 6 = - 5

The equation becomes

y = 3x - 5

Answer:

The answer to your question is   y = 1/12 (x - 5)²

Step-by-step explanation:

Data

directrix   y = -3

focus       (5, 3)

Process

1.- Graph the directrix and focus to determine if the parabola is vertical or horizontal.

From the graph we know that it is a vertical parabola with equation

                  (x - h)² = 4p(y - k)

2.- From the graph we know that p = 3 because the distance from the focus to the directrix is 6 and p = 6/2.

3.- The vertex (5, 0)

4.- Substitution

                 (x - 5)² = 4(3)(y - 0)

5.- Simplification

                (x - 5)² = 12y

6.- Result

                y = 1/12 (x - 5)²

Answer:

y = 1/12 (x - 5)²

Step-by-step explanation:

Final answer:

To solve for the distance, velocity, and acceleration of a hammer dropped from a hovering helicopter, calculations based on the given formula s(t) = 1818t^2 are used, yielding a fall of 29128 feet in 4 seconds, a velocity of 14512 feet/sec at 4 seconds, and a constant acceleration of 3636 feet/sec^2.

Explanation:

When an object is dropped on a certain earth-like planet, the distance it falls in t seconds, assuming that air resistance is negligible, is given by s(t) = 1818t2, where s(t) is in feet. To solve the problem involving a medic's reflex hammer dropped from a hovering helicopter:

(a) To find how far the hammer falls in 4 seconds, substitute t = 4 into the equation: s(4) = 1818(4)2 = 29128 feet.

(b) The velocity of the hammer after 4 seconds can be found using the derivative of s(t), v(t) = 2×1818×t. Substituting t = 4, v(4) = 2×1818×4 = 14512 feet/sec.

(c) The acceleration of the hammer is constant and equal to 2×1818 feet/sec2 = 3636 feet/sec2, which is twice the coefficient in the equation for s(t).

These calculations demonstrate the principles of kinematics, specifically how position, velocity, and acceleration relate to one another for an object in free fall on an earth-like planet with negligible air resistance.

Answer:

Vertical compression, horizontal shift left, vertical shift down

Step-by-step explanation:

[tex]f(x) = 3^x => g(x) = \frac{1}{2} *2^{x+3} -5[/tex]

Let's break down what happened here:

[tex]\frac{1}{2}[/tex]  - This indicates a vertical compression

[tex]2^{x+3}\\[/tex]   - This indicates a horizontal shift left

-5    - This indicates a vertical shift down

Final answer:

Transforming f(x) to g(x) involves a vertical compression by ½, a horizontal shift left by 3 units, and a vertical shift down by 5 units. There is also an exponential base change, but it does not correspond directly to the given transformation options.

Explanation:

To transform the function f(x) = 3x into g(x) = ½ · 2x+3 - 5, let's analyze each part of the transformation. Break down g(x) into its components to determine the transformations:

Based on this analysis, the correct transformations that occurred are a vertical compression, a horizontal shift left, and a vertical shift down.

Answer:

A

Step-by-step explanation:

y = mx + c

y = -½x + 1

Answer:

Step-by-step explanation:

concentration = amount of salt/solution

A) Initial concentration= 90/1000 = 0.09

Q = quantity of salt

Q(0) = 90 kg

Inflow rate = 8 l/min

Outflow rate = 8 l/min

Solution = 1000 L at any time t.

Salt inflow = 0.045 * 8 per minute

= 0.36 kg per minute

This is mixed and drains from the tank.

Outflow = [tex]\frac{Q(t)}{1000}[/tex]

Thus rate of change of salt

Q'(t) = inflow - outflow = [tex]0.36-\frac{Q(t)}{1000} \\=\frac{360-Q(t)}{1000}[/tex]

Separate the variables and integrate

[tex]\frac{1000dQ}{360-q(t)} =dt\\-1000 ln |360-Q(t)| = t+C\\ln |360-Q(t)| = -0.001+C'\\360-Q(t) = Ae^{-0.001t} \\Q(t) = 360-Ae^{-0.001t}[/tex]

Use the fact that Q(0) = 90

90 = 360-A

A = 270

So

[tex]Q(t) = 360-270e^{-0.001t}[/tex]

B) Q(t) = 360-270e^-0.004  = 91.07784

C) When t approaches infinity, we get

Q(t) tends to 360

So concentration =360/1000 = 0.36

Final answer:

a) The initial concentration of the solution in the tank is 0.09 kg/L. b) The amount of salt in the tank after 4 hours is 3.6 kg. c) The concentration of salt in the solution in the tank approaches 0.045 kg/L as time approaches infinity.

Explanation:

a) To find the concentration of the solution in the tank initially, we need to calculate the total mass of salt and water in the tank. The concentration is the mass of salt divided by the volume of water. Since 1 liter of water weighs 1 kg, the initial concentration of the solution in the tank is 90 kg of salt divided by 1000 kg of water, which is 0.09 kg/L.

b) To find the amount of salt in the tank after 4 hours, we need to calculate the amount of salt entering the tank and the amount of salt leaving the tank in that time. The amount of salt entering the tank is the concentration of the incoming solution (0.045 kg/L) multiplied by the rate of flow (8 L/min) and the time (4 hours = 240 minutes). This gives us 0.045 kg/L × 8 L/min × 240 min = 86.4 kg. The amount of salt leaving the tank is the concentration of the solution in the tank (0.09 kg/L) multiplied by the rate of flow (8 L/min) and the time (4 hours = 240 minutes). This gives us 0.09 kg/L × 8 L/min × 240 min = 172.8 kg. Therefore, the amount of salt in the tank after 4 hours is the initial amount of salt (90 kg) plus the amount of salt entering the tank (86.4 kg) minus the amount of salt leaving the tank (172.8 kg), which is 3.6 kg.

c) As time approaches infinity, the concentration of salt in the solution in the tank will approach the concentration of the incoming solution, which is 0.045 kg/L.