Answer:
The value of x component changes at a rate of
units per second
Step-by-step explanation:
We are given that 
Differentiating on both sides with respect to time we get

It is given that
Solving for
we get

Answer:
C≈27 feet
Step-by-step explanation:
A=πr²
A/π=r²
√A/π =r or –√A/π=r (refused)
then r =√(A/π) =√(58/π) =4.297829403 feet
C=2πr=2π(4.297829403)=27.00405856≈27 feet
Lets say, for ease, that the vat can hold a total of 70 gallons (or whatever you would like to use.) Use whatever number you want, I just picked this because it gives us a lot of clean numbers.
Now, if the inlet can fill it in 7 hours, that means that it is adding 10 gallons per hour. (70 gal/7 hours = 10 gal/hr)
For the outlet, use the same process, and you find that it drains the vat at 7 gallons per hour.
So, if you subtract the outlet from the inlet, you get 10 - 7 = 3 gallons per hour added.
Now just divide the size of the vat by that number, and you find your answer.
70 gallons / 3 gallons per hour = 23 1/3 hours.