M7MBA wrote:Is x < y?
(1) xz < yz
(2) -3x > 6y
The OA is E.
Could someone help me? Please. I don't have an idea of how to solve this DS question. <i class="em em-cry"></i>
This Yes/No Data Sufficiency question can be answered by Plugging In.
Statement (1):
Plug In a value for z.
If z = -2, then dividing both sides of the inequality by z will flip the inequality, so that x > y. In this case, the answer is No.
If z = 2, then dividing both sides of the inequality by z yields x < y. In this case the answer is Yes.
The information in Statement (1) is insufficient to answer the question, so write down BCE.
Statement (2):
Simplify the inequality. Divide both sides by -3, so that x < -2y.
Plug In a value for y.
If y = 1, then x < -2. In this case, x < y, so the answer is Yes.
If y = -1, then x < 2. In this case, it's possible that x =1 and y = -1, in which case x > y and the answer is No.
The information in Statement (2) is insufficient to answer the question, so eliminate choice B.
Both statements together:
Statement (1) provides no information about the relative values of x and y, since x < y if z is positive, and x > y if z is negative.
In other words, any values of x and y will satisfy the first statement, so when both statements are evaluated together, Statement (1) adds no relevant information.
Thus, evaluating both statements together is tantamount to evaluating Statement (2), which has already been proved insufficient.
The correct answer is choice
E.
