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GRE Quantitative Practice, Numeric Entry

Question 4

At a minimum, how many complete buckets of water, each with a capacity of 3 cubic meters, are needed to fill an empty cylindrical tank whose height is 3 meters and whose base has a radius of 2 meters?

Note: The value of pi (π) ≈ 3.14.


Explanatory Answer

The volume of the cylindrical tank is (h)(πr2), where h is the cylinder's height and r is its radius:

V = (h)(πr2) = (3)(4)π = 12π

The value of π is given as approximately 3.14. Accordingly, the large tank's volume is between 37 and 38 cubic meters (12 × 3.14 = 37.68). With a volume of 3 cubic meters each, 13 buckets of water are needed to fill the larger tank in its entirety. (12 buckets amount to 36 cubic meters of water, which is not enough.) To gain credit for answering the question correctly, you would need to enter the number 13 in the numeric-entry box.

calculatorNOTE: During the Quantitative Reasoning sections of the exam you'll have access to an on-screen calculator, which you should use to answer questions like this one.