Answer:
![A(x) = 243](https://tex.z-dn.net/?f=A%28x%29%20%3D%20243)
Step-by-step explanation:
Given
![f(x) = x^3 - 9x](https://tex.z-dn.net/?f=f%28x%29%20%3D%20x%5E3%20-%209x)
![Interval: (12,6)](https://tex.z-dn.net/?f=Interval%3A%20%2812%2C6%29)
Required
Determine the average rate of change
Average rate is calculated as thus;
![A(x) = \frac{f(b) - f(a)}{b - a}](https://tex.z-dn.net/?f=A%28x%29%20%3D%20%5Cfrac%7Bf%28b%29%20-%20f%28a%29%7D%7Bb%20-%20a%7D)
<em>In this case; b = 12 and a = 6</em>
Calculating f(12)
![f(12) = 12^3 - 9 * 12](https://tex.z-dn.net/?f=f%2812%29%20%3D%2012%5E3%20-%209%20%2A%2012)
![f(12) = 1728 - 108](https://tex.z-dn.net/?f=f%2812%29%20%3D%201728%20-%20108)
![f(12) = 1620](https://tex.z-dn.net/?f=f%2812%29%20%3D%201620)
Calculating f(6)
![f(6) = 6^3 - 9 * 6](https://tex.z-dn.net/?f=f%286%29%20%3D%206%5E3%20-%209%20%2A%206)
![f(6) = 216 - 54](https://tex.z-dn.net/?f=f%286%29%20%3D%20216%20-%2054)
![f(6) = 162](https://tex.z-dn.net/?f=f%286%29%20%3D%20162)
Substitute 12 for b and 6 for a in ![A(x) = \frac{f(b) - f(a)}{b - a}](https://tex.z-dn.net/?f=A%28x%29%20%3D%20%5Cfrac%7Bf%28b%29%20-%20f%28a%29%7D%7Bb%20-%20a%7D)
![A(x) = \frac{f(12) - f(6)}{12 - 6}](https://tex.z-dn.net/?f=A%28x%29%20%3D%20%5Cfrac%7Bf%2812%29%20-%20f%286%29%7D%7B12%20-%206%7D)
Substitute values for f(6) and f(12)
![A(x) = \frac{1620 - 162}{12 - 6}](https://tex.z-dn.net/?f=A%28x%29%20%3D%20%5Cfrac%7B1620%20-%20162%7D%7B12%20-%206%7D)
![A(x) = \frac{1458}{ 6}](https://tex.z-dn.net/?f=A%28x%29%20%3D%20%5Cfrac%7B1458%7D%7B%206%7D)
![A(x) = 243](https://tex.z-dn.net/?f=A%28x%29%20%3D%20243)
All these given roots are contained in option C.
The given equation is :
![9x^{3}+9x^{2}-4x-4=0](https://tex.z-dn.net/?f=9x%5E%7B3%7D%2B9x%5E%7B2%7D-4x-4%3D0)
![9x^{2}(x+1)-4(x+1)=0](https://tex.z-dn.net/?f=9x%5E%7B2%7D%28x%2B1%29-4%28x%2B1%29%3D0)
![(9x^{2}-4)(x+1)=0](https://tex.z-dn.net/?f=%289x%5E%7B2%7D-4%29%28x%2B1%29%3D0)
![9x^{2}-4=0,x+1=0](https://tex.z-dn.net/?f=9x%5E%7B2%7D-4%3D0%2Cx%2B1%3D0)
![x^{2}=\frac{4}{9},x=-1](https://tex.z-dn.net/?f=x%5E%7B2%7D%3D%5Cfrac%7B4%7D%7B9%7D%2Cx%3D-1)
![x=\frac{2}{3},x=-1](https://tex.z-dn.net/?f=x%3D%5Cfrac%7B2%7D%7B3%7D%2Cx%3D-1)
Roots = ![-1,\frac{-2}{3} ,\frac{2}{3}](https://tex.z-dn.net/?f=-1%2C%5Cfrac%7B-2%7D%7B3%7D%20%2C%5Cfrac%7B2%7D%7B3%7D)
Hence these lie in between ![(\frac{-3}{2} ,\frac{3}{2})](https://tex.z-dn.net/?f=%28%5Cfrac%7B-3%7D%7B2%7D%20%2C%5Cfrac%7B3%7D%7B2%7D%29)
To solve this, set up the equation, 90% of x being .9*x=57. Then, solve for x, x=57/.9=
![6 \frac{1}{3}](https://tex.z-dn.net/?f=6%20%5Cfrac%7B1%7D%7B3%7D%20)
=6.333
Answer:
Option B
Both distributions are nearly symmetric, so the mean and the standard deviation are the best measures for comparison.
Step-by-step explanation: