## anonymous one year ago An oil tank has to be drained for maintenance. The tank is shaped like a cylinder that is 3.5 ft long with a diameter of 1.4 ft . Suppose oil is drained at a rate of 2.1 ft3 per minute. If the tank starts completely full, how many minutes will it take to empty the tank? Use the value 3.14 for π , and round your answer to the nearest minute. Do not round any intermediate computations.

1. anonymous

$V=\frac{ \pi d^2h }{ 4 }$

2. anonymous

Then divide by the volume by the rate to find the time

3. anonymous

is that the correct formula ? is it supposed to be r^2 instead of d^2?

4. anonymous

& why divide by 4?

5. anonymous

It's the correct formula. You can also use V = πr²h. I used the one with d because they gave the diameter. r = d/2, so r² = d²/4