GMAT Quantitative Reasoning Practice Test 7

Question : 78 of 100

Marks: +1, -0

X, Y

and

Z

are three numbers. If

Y=5

,
what is their sum?
(1)

X-Z=10

.
(2)

Z-Y=15

Statement (1) BY ITSELF is sufficient to answer the question, but statement (2) by itself is not.
Statement (2) BY ITSELF is sufficient to answer the question, but statement (1) by itself is not.
Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, even though NEITHER statement BY ITSELF is sufficient.
Either statement BY ITSELF is sufficient to answer the question.
Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question, requiring more data pertaining to the problem.

Solution:

We need to find the value of

X+Y+Z

Y

is given to us so we need the value of

(X+Z)

.
Statement (1) is insufficient by itself since we are given the value of

(X-Z)

and

{\not}(X+Z)

.
From statement (2) we can find the value of

Z

, and from there return to statement (1) and find the value of

X

. Both statements, taken together, are sufficient.

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