Speed problem

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Speed problem

by Mo2men » Mon Jan 22, 2018 12:20 pm
At what speed was Erik running when he was at the halfway point of his route?

1. Erik's route was 10 miles long and took him 2 hours to complete.
2. Erik ran at an average speed of 5 miles per hour on the route

OA: E
Source: Veritas
Source: — Data Sufficiency |

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Erik

by GMATGuruNY » Mon Jan 22, 2018 12:33 pm
Mo2men wrote:At what speed was Erik running when he was at the halfway point of his route?

1. Erik's route was 10 miles long and took him 2 hours to complete.
2. Erik ran at an average speed of 5 miles per hour on the route
Statements combined:
Each statement conveys the same information: that the average speed for the whole trip was 5 miles per hour.
The AVERAGE speed for the whole trip does not constrain the speed AT THE HALWAY POINT.
At the halfway point, the speed could be ANY NONNEGATIVE VALUE.
Thus, the two statements combined are INSUFFICIENT.

The correct answer is E.
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by Mo2men » Mon Jan 22, 2018 12:35 pm
GMATGuruNY wrote:
Mo2men wrote:At what speed was Erik running when he was at the halfway point of his route?

1. Erik's route was 10 miles long and took him 2 hours to complete.
2. Erik ran at an average speed of 5 miles per hour on the route
Statements combined:
Each statement conveys the same information: that the average speed for the whole trip was 5 miles per hour.
The AVERAGE speed for the whole trip does not constrain the speed AT THE HALWAY POINT.
At the halfway point, the speed could be ANY VALUE.
Thus, the two statements combined are INSUFFICIENT.

The correct answer is E.
Thanks Mitch for your solution.

if the question asks for average speed, could statement 2 be sufficient ?
Thanks

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speed problem

by GMATGuruNY » Mon Jan 22, 2018 12:44 pm
Mo2men wrote:Thanks Mitch for your solution.

if the question asks for average speed, could statement 2 be sufficient ?
Thanks
Proposed question stem: What was Erik's average speed?
Statement 2: Erik ran at an average speed of 5 miles per hour.
Here, Statement 2 gives a direct answer to the question stem.
This scenario is not plausible.
A DS statement will never directly answer the question stem.
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