Gnpth wrote:
A closed cylindrical tank contains 16 \(\pi\) cubic feet of water and is filled to one-quarter of its capacity. When the tank is placed upright on its circular base on level ground, the height of the water in the tank is equal to the diameter of the tanks base. What is the radius of the tank?
(A) 1
(B) 2
(C) \(2\sqrt{2}\)
(D) 4
(E) 8
Total capacity = 64\(\pi\), which means that 16 \(\pi\) is 1/4th of the volume, which is \(\pi\)r^2*h/4. Therefore, \(\pi\)r^2*h/4=16\(\pi\). This leaves us with r^2*h=64 and h=64/r^2.
"When the tank is placed upright on its circular base on level ground, the height of the water in the tank is equal to the diameter of the tanks base. What is the radius of the tank?" When the tank is placed upright, the height of water (1/4*h)=2r(diameter). Substituting for h we get, 1/4*64/r^2=2r. Solving for r we get r=2, which is answer B.
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"Hardwork is the easiest way to success." - Aviram
One more shot at the GMAT...aiming for a more balanced score.