Given:


To find:
The rate of change in volume at 
Solution:
We know that, volume of a cone is

Differentiate with respect to t.
![\dfrac{dV}{dt}=\dfrac{1}{3}\pi\times \left[(r^2\dfrac{dh}{dt}) + h(2r\dfrac{dr}{dt})\right]](https://tex.z-dn.net/?f=%5Cdfrac%7BdV%7D%7Bdt%7D%3D%5Cdfrac%7B1%7D%7B3%7D%5Cpi%5Ctimes%20%5Cleft%5B%28r%5E2%5Cdfrac%7Bdh%7D%7Bdt%7D%29%20%2B%20h%282r%5Cdfrac%7Bdr%7D%7Bdt%7D%29%5Cright%5D)
Substitute the given values.
![\dfrac{dV}{dt}=\dfrac{1}{3}\times \dfrac{22}{7}\times \left[(120)^2(-2.1) +175(2)(120)(1.4)\right]](https://tex.z-dn.net/?f=%5Cdfrac%7BdV%7D%7Bdt%7D%3D%5Cdfrac%7B1%7D%7B3%7D%5Ctimes%20%5Cdfrac%7B22%7D%7B7%7D%5Ctimes%20%5Cleft%5B%28120%29%5E2%28-2.1%29%20%2B175%282%29%28120%29%281.4%29%5Cright%5D)
![\dfrac{dV}{dt}=\dfrac{22}{21}\times \left[-30240+58800\right]](https://tex.z-dn.net/?f=%5Cdfrac%7BdV%7D%7Bdt%7D%3D%5Cdfrac%7B22%7D%7B21%7D%5Ctimes%20%5Cleft%5B-30240%2B58800%5Cright%5D)


Therefore, the volume of decreased by 29920 cubic inches per second.
Answer
The function represents the car’s value after x years.
f(x) = 20,000(0.85)x
Reason
As given
Terrence buys a new car for $20,000.
The value of the car depreciates by 15% each year.
15 % is written in the decimal form

= 0.15
Thus
The decrease in the value of car is represented by = a (1 - r)× t
Where a is the original cost
r is the depreciates rate in decimal form
t is time in years.
Here a = $20000 ,r = 0.15 , t = x years
The value of car after x years = 20,000 (1 -0.15)x
= 20000(0.85)x
Therefore the the value of the car after x years is represented by f(x) = 20,000(0.85)x .
Benchmark are numbers that are used as standards to which the rest of the data is compared to. When counting numbers using a number line, the benchmark numbers are the intervals written on the axis. For benchmark numbers of 10, the number line on top of the attached picture is shown. Starting from 170, the tick marks are added by 10, such that the next numbers are 180, 190, 200, and so on and so forth. When you want to find 410, just find the benchmark number 410.
The same applies to benchmark numbers in intervals of 100. If you want to find 170, used the benchmark numbers 100 and 200. Then, you estimate at which point represents 170. For 410, you base on the benchmark numbers 400 and 500.
Let's use J for James's age and A for Austin's age. The equations are:
J = A - 4
3J + A² = 28
Just plug (A - 4) in the place of J in the second equation. This gives you:
3(A - 4) + A² = 28
-->
A² + 3A - 12 = 28
-->
A² + 3A - 40 = 0
-->
(A - 5)(A + 8) = 0
-->
A = 5 or -8
-8 is nonsense, so Austin is 5 years old. Therefore, James is 1 year old.
The correct answer is the choice that you have selected, the third choice.
When, we are looking at the residuals for a regression line, we always want to see the points balance like in the third choice. This means that the equation that we found is right in the middle of the points.