Scott Woodbury-Stewart

GMAT OFFICIAL GUIDE DS – Is x…

Is x…

Solution:

We must determine whether x = 1/y.

Statement One Alone: 

xy = 1

Manipulating the equation in statement one by dividing both sides by y we have:

x = 1/y

Note that we were able to divide both sides of the equation by y because we know that y cannot be equal to 0. (If this were not the case, then we would not be able to perform this step.)

Statement one is sufficient to answer the question. We can eliminate answer choices B, C, and E.

Statement Two Alone: 

1/(xy) = 1

Manipulating the equation in statement two by multiplying both sides by x we have

1/y = x

Statement two alone is sufficient to answer the question.

Answer: D 

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