fambrini wrote:Did it take Ann more than 2 hours to walk a distance of 10 miles along a certain trail? (1 mile = 1.6 kilometers)
1) Ann walked this distance at an average rate of less than 6.4 kilometers per hour.
2) On average, it took Ann more than 9 minutes per kilometer to walk the distance.
OA: D
Target question: Did it take Ann more than 2 hours to walk a distance of 10 miles?
This is a great candidate for
rephrasing the target question.
Aside: We have a video with tips on rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100
If Ann were able to walk 10 miles in EXACTLY 2 hours, then Ann's average speed would EQUAL 5 miles per hour.
So, if it were to take Ann MORE THAN 2 hours, then Ann's average speed would be LESS THAN 5 miles per hour.
This means we can rephrase the target question as...
REPHRASED target question: Is Ann's average speed less than 5 miles per hour?
Since the two statements are in terms of
kilometers, let's rephrase the target question one more time...
5 miles = 8 kilometers, so 5 miles per hour = 8 kilometers per hour.
RE-REPHRASED target question: Is Ann's average speed less than 8 KILOMETERS per hour?
At this point, it will be relatively easy to handle the two statements.
Statement 1: Ann walked this distance at an average rate of less than 6.4 kilometer per hour.
If Ann walked slower than 6.4 kilometer per hour, we can be CERTAIN that
Ann's average speed less is than 8 kilometers per hour
Since we can answer the
RE-REPHRASED target question with certainty, statement 1 is SUFFICIENT
Statement 2: On average, it took Ann more than 9 minutes per kilometer to walk this distance.
Let's see what it means for Ann to walk 1 kilometer in
EXACTLY 9 minutes.
This means Ann walks 7 kilometers in 63 minutes, which means he/she walks a little SLOWER than 7 kilometers per HOUR.
Since we're told that it took Ann MORE than 9 minutes per kilometer, we can be CERTAIN that
Ann's average speed less is than 8 kilometers per hour
Since we can answer the
RE-REPHRASED target question with certainty, statement 2 is SUFFICIENT
Answer =
D
Cheers,
Brent
