Hi binaras,
There's a discussion of this DS question here:
https://www.beatthegmat.com/inequality-t272612.html
GMAT assassins aren't born, they're made,
Rich
Is V>0?
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Source: Beat The GMAT — Data Sufficiency |
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Nice question.If mv < pv < 0, is v > 0?
1) m < p
2) m < 0
Target question: Is v > 0
Given: mv < pv < 0
Statement 1: m < p
IMPORTANT: Notice what happens if we take mv < pv and divide both sides by v.
The resulting inequality will depend on whether v is NEGATIVE or POSITIVE. So, let's consider two cases:
case a: v is NEGATIVE.
When we take mv < pv and divide both sides by v, we get m > p
We changed the direction of the inequality sign since we divided by a NEGATIVE value.
case b: v is POSITIVE.
When we take mv < pv and divide both sides by v, we get m < p
The direction of the inequality sign stayed the same since we divided by a POSITIVE value.
Statement 1 tells us that m < p, which means we can rule out case a.
So, we conclude that v is POSITIVE
In other words, v > 0
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: m < 0
We're told that mv < pv < 0, which means that mv < 0
In other words, the product mv is NEGATIVE
Statement 2 tell us that m is NEGATIVE
In order for the product mv to be NEGATIVE, v must be positive
In other words, v > 0
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Answer = D
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Brent
Brent Hanneson - Creator of GMATPrepNow.com
