Volume of Cylinder Formula

GRE Quant Problem Solving
1

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Hi all,

I am trying to understand why Greg is solving the volume of a cylinder with 𝞹 on both sides of the equation. From my understanding, the formula for finding the volume of a cylinder is h𝞹r^2 = volume, so why would Greg have 𝞹 on both sides of the equation?

Thanks!

2

The question starts with that a closed cylindrical tank contains 36 pi cubic feet water and is half-filled.
So, a full filled closed cylindrical tank will contain double that value, thus, 72 pi.

Now, volume of cylinder is = \pi r^2h -->Eq1
And the volume of the tank given to us is 72\pi---->Eq2

Equate both equation to get the value of radius

3

Hi - thank you for clarifying. Of course I made a mistake and overlooked the question while reading and thought it stated that the tank contains 36 cubic feet - not 36 pi cubic feet. Definitely need to slow down when reading questions.

Thanks again!