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This series is designed to help you step up your Data Sufficiency practice while we all spend a little extra time at home during the coronavirus situation; I’m going to publish one practice Data Sufficiency question each day! You can choose to do all of them, or none of them. 

Click on the tag “Social Distancing DS Challenge” at the bottom of this post to see all of the questions in this series! 

And remember to take whatever precautions you need to stay healthy over the next few weeks! 

Question #28

The interior of a rectangular box is 54 inches long, 27 inches wide, and 9 inches high. The box is filled with x cylindrical tubes of tennis balls that stand upright in rows and columns such that all the cylinders are touching and there is no additional space for extra tubes. If the tubes are 9 inches high, what is the value of x?

(1) 18 tubes fit exactly along the interior length of the box.

(2) Each of the tubes has a diameter of 3 inches.

 Explanation

With statement (1), we can determine x by finding the diameter of each tube. We know the length is 54 inches. If 18 tubes fit along that edge, we know the diameter is: ⁵⁴/₁₈ = 3 We can then figure out that ²⁷/₃ = 9 tubes would fit along the width. And from there, we can determine x (but to save time, we won’t work out the math). Sufficient.

And statement (2) gives us the diameter outright, and we already know we can find x using the diameter with the given dimensions. Sufficient. The correct answer is (D).