Digital PSAT Math Practice Question 49: Answer and Explanation

Question: 49

A cube with edge length x has all of its edges doubled. Suppose the volume of the original cube is V cubic inches. What is the volume of the new cube in terms of the original cube?

• A. 2V
• B. 4V
• C. 8V
• D. 16V

Correct Answer: C

Explanation:

(C) Each edge of the cube is doubled. So instead of each edge having a length of x, each edge now has a length of 2x. The volume formula for a cube is V = x³. The original cube has a volume of x³. The new cube has a volume of (2x)³ = 2³ x³ = 8x³. So the volume of the new cube is 8 times the volume of the original cube, which is 8V.