Scott Woodbury-Stewart

GMAT OFFICIAL GUIDE PS – A positive number x is multiplied by 2, and this product…

A positive number x is multiplied by 2, and this product…

Solution:

We need to produce an equation from the information given in the problem stem. We are first given that x is multiplied by 2 and then the product is divided by 3. This gives us:

2x/3

Next we are given that the positive square root of the result (which is 2x/3) is equal to x. This gives us

√(2x/3) = x

2x/3 = x^2

2x = 3x^2

3x^2 – 2x = 0

x(3x – 2) = 0

x = 0 or

3x – 2 = 0

3x = 2

x = 2/3

Because x is positive, x = 2/3.

Answer: D