Answer:
1 C
2 D and B
3 46
Step-by-step explanation:
hope that helps if not sorry<3
Answer:
the rate of change of the water depth when the water depth is 10 ft is; ![\mathbf{\dfrac{dh}{dt} = \dfrac{-25}{100 \pi} \ \ ft/s}](https://tex.z-dn.net/?f=%5Cmathbf%7B%5Cdfrac%7Bdh%7D%7Bdt%7D%20%20%3D%20%5Cdfrac%7B-25%7D%7B100%20%20%5Cpi%7D%20%5C%20%20%5C%20ft%2Fs%7D)
Step-by-step explanation:
Given that:
the inverted conical water tank with a height of 20 ft and a radius of 8 ft is drained through a hole in the vertex (bottom) at a rate of 4 ft^3/sec.
We are meant to find the rate of change of the water depth when the water depth is 10 ft.
The diagrammatic expression below clearly interprets the question.
From the image below, assuming h = the depth of the tank at a time t and r = radius of the cone shaped at a time t
Then the similar triangles ΔOCD and ΔOAB is as follows:
( similar triangle property)
![\dfrac{h}{r}= \dfrac{5}{2}](https://tex.z-dn.net/?f=%5Cdfrac%7Bh%7D%7Br%7D%3D%20%5Cdfrac%7B5%7D%7B2%7D)
![\dfrac{h}{r}= 2.5](https://tex.z-dn.net/?f=%5Cdfrac%7Bh%7D%7Br%7D%3D%202.5)
h = 2.5r
![r = \dfrac{h}{2.5}](https://tex.z-dn.net/?f=r%20%3D%20%5Cdfrac%7Bh%7D%7B2.5%7D)
The volume of the water in the tank is represented by the equation:
![V = \dfrac{1}{3} \pi r^2 h](https://tex.z-dn.net/?f=V%20%3D%20%5Cdfrac%7B1%7D%7B3%7D%20%5Cpi%20r%5E2%20h)
![V = \dfrac{1}{3} \pi (\dfrac{h^2}{6.25}) h](https://tex.z-dn.net/?f=V%20%3D%20%5Cdfrac%7B1%7D%7B3%7D%20%5Cpi%20%28%5Cdfrac%7Bh%5E2%7D%7B6.25%7D%29%20h)
![V = \dfrac{1}{18.75} \pi \ h^3](https://tex.z-dn.net/?f=V%20%3D%20%5Cdfrac%7B1%7D%7B18.75%7D%20%5Cpi%20%5C%20h%5E3)
The rate of change of the water depth is :
![\dfrac{dv}{dt}= \dfrac{\pi r^2}{6.25}\ \dfrac{dh}{dt}](https://tex.z-dn.net/?f=%5Cdfrac%7Bdv%7D%7Bdt%7D%3D%20%5Cdfrac%7B%5Cpi%20r%5E2%7D%7B6.25%7D%5C%20%20%5Cdfrac%7Bdh%7D%7Bdt%7D)
Since the water is drained through a hole in the vertex (bottom) at a rate of 4 ft^3/sec
Then,
![\dfrac{dv}{dt}= - 4 \ ft^3/sec](https://tex.z-dn.net/?f=%5Cdfrac%7Bdv%7D%7Bdt%7D%3D%20-%204%20%20%5C%20ft%5E3%2Fsec)
Therefore,
![-4 = \dfrac{\pi r^2}{6.25}\ \dfrac{dh}{dt}](https://tex.z-dn.net/?f=-4%20%3D%20%5Cdfrac%7B%5Cpi%20r%5E2%7D%7B6.25%7D%5C%20%20%5Cdfrac%7Bdh%7D%7Bdt%7D)
the rate of change of the water at depth h = 10 ft is:
![-4 = \dfrac{ 100 \ \pi }{6.25}\ \dfrac{dh}{dt}](https://tex.z-dn.net/?f=-4%20%3D%20%5Cdfrac%7B%20100%20%5C%20%5Cpi%20%7D%7B6.25%7D%5C%20%20%5Cdfrac%7Bdh%7D%7Bdt%7D)
![100 \pi \dfrac{dh}{dt} = -4 \times 6.25](https://tex.z-dn.net/?f=100%20%5Cpi%20%5Cdfrac%7Bdh%7D%7Bdt%7D%20%20%3D%20-4%20%5Ctimes%206.25)
![100 \pi \dfrac{dh}{dt} = -25](https://tex.z-dn.net/?f=100%20%20%5Cpi%20%5Cdfrac%7Bdh%7D%7Bdt%7D%20%20%3D%20-25)
![\dfrac{dh}{dt} = \dfrac{-25}{100 \pi}](https://tex.z-dn.net/?f=%5Cdfrac%7Bdh%7D%7Bdt%7D%20%20%3D%20%5Cdfrac%7B-25%7D%7B100%20%20%5Cpi%7D)
Thus, the rate of change of the water depth when the water depth is 10 ft is; ![\mathtt{\dfrac{dh}{dt} = \dfrac{-25}{100 \pi} \ \ ft/s}](https://tex.z-dn.net/?f=%5Cmathtt%7B%5Cdfrac%7Bdh%7D%7Bdt%7D%20%20%3D%20%5Cdfrac%7B-25%7D%7B100%20%20%5Cpi%7D%20%5C%20%20%5C%20ft%2Fs%7D)
Answer:
if there are answer choices i would put the closest one to 16
There’s not enough info — you only have SS.
Answer:
D
Step-by-step explanation:
<em>The statements are shown below:</em>
<em>A) She used the wrong number as a repeated factor and should have evaluated -2x2x2x2x2x2x2x2.
</em>
<em>B) She used the wrong number as a repeated factor and should have evaluated -(8x8).
</em>
<em>C) She misinterpreted the exponential form and should have multiplied -2 and 8.
</em>
<em>D) She made a sign error when multiplying and should have had 256 as a final answer.</em>
<em />
<u>Solution:</u>
<u />
The problem to simplify is:
![(-2)^{8}](https://tex.z-dn.net/?f=%28-2%29%5E%7B8%7D)
Haley's steps are shown below:
![(-2)^{8}=(-2)(-2)(-2)(-2)(-2)(-2)(-2)(-2)=-256](https://tex.z-dn.net/?f=%28-2%29%5E%7B8%7D%3D%28-2%29%28-2%29%28-2%29%28-2%29%28-2%29%28-2%29%28-2%29%28-2%29%3D-256)
Generally,
is actually "a" multiplied "b" times.
So, Haley wrote "-2" eight times multiplied together. That is okay.
Now,
We are dealing with negative numbers.
- When negative numbers are multiplied "odd" number of times, the answer is negative.
- When negative numbers are multiplied "even" number of times, the answer is positive.
Haley wrote "-2" eight times, which is EVEN number of times, so the answer would be POSITIVE. But, Haley's answer is negative. Which is wrong. But "256" is right.
Haley's error is:
Answer choice D