Scott Woodbury-Stewart

GMAT OFFICIAL GUIDE DS – What is the cube root…

What is the cube root…

Solution:

We need to determine the cube root of w. Thus, if we have a value for w, we can determine the value of the cube root of w.

Statement One Alone:

The 5th root of w is 64.

Recall that the nth root of a number is the number raised to the 1/n power; we can set up an equation with the information from statement one.

w^(1/5) = 64

Now raise both sides of the equation to the 5th power.

w = 64^5

Since we know that we have a unique value for w, we can stop here. This is enough information to enable us to determine the value of the cube root of w. Statement one provides enough information to answer the question. We can eliminate answer choices B, C, and E.

Statement Two Alone:

The 15th root of w is 4.

We can set up an equation with the information from statement two.

w^(1/15) = 4

w = 4^15

Since we know that we have a unique value for w, we can stop here. This is enough information to enable us to determine the value of the cube root of w. Statement two is also sufficient.

Answer: D