word problem

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word problem

by sud21 » Thu Jan 12, 2012 4:38 am
In the number line, is point P between Q and Z?
1). The product of P and Q is greater than 0
2). The product of P and Z is less than 0
Source: — Data Sufficiency |

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by sud21 » Tue Jan 31, 2012 7:41 pm
The three points P,Q,Z can be anywhere. Those can be left or right of zero, that is, those can be negative or positive or those can be a mix of positive and negative.

St.(1) Can't be determined.

St.(2) Can't be determined.

Ans.E

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by Brent@GMATPrepNow » Wed Feb 01, 2012 7:07 am
sud21 wrote:In the number line, is point P between Q and Z?
1). The product of P and Q is greater than 0
2). The product of P and Z is less than 0
To answer this question, it might be useful to use a number line to show the different cases that follow from each statement.

Statement 1: The product of P and Q is greater than 0
i.e., the product is positive. So:
case a) either P & Q are both negative
case b) P & Q are both positive

On a number line, we get:
case a) _____P_Q____0__________
case b) ____________0________P_Q__

Since we have no information about Z, we cannot answer the target question with any certainty.
So, statement 1 is NOT SUFFICIENT


Statement 2: The product of P and Z is less than 0
i.e., the product is negative.
So one is positive and one is negative

On a number line, we get:
case a) _____P______0____Z______
case b) _____Z______0____P______

Since we have no information about Q, we cannot answer the target question with any certainty.
So, statement 2 is NOT SUFFICIENT


Statements 1& 2:
Several cases are possible. Here are two:

On a number line, we get:
case a) _____Z______0____P__Q____ (P is between Q and Z)
case b) _____Z______0____Q__P____ (P is not between Q and Z)
Since we cannot answer the target question with certainty, statements 1 & 2 are NOT SUFFICIENT, so the answer is E

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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