Data Sufficiency

BTGmoderatorDC wrote: ↑

Sun Jan 02, 2022 11:09 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 Prep

IMPORTANT: The two statements essentially provide the exact same information.
If it took Erik 2 hours to travel 10 miles, we can conclude that his average speed was 5 miles per hour.
When the two statements provide the same information in a Data Sufficiency question, the correct answer must be either D or E (see the video below for more on this)

Target question: At what speed was Erik running when he was at the halfway point of his route?

Statements 1 and 2 combined
There are several scenarios that satisfy BOTH statements. Here are two:
Case a: Erik traveled the first 1 mile at 1 mile per hour, and then traveled the last 9 miles at 9 miles per hour. So, at the halfway mark (upon completion of the 5th mile), Erik was running at a speed of 9 mph
Case b: Erik traveled the first 2 miles at 2 miles per hour, and then traveled the last 8 miles at 8 miles per hour. So, at the halfway mark (upon completion of the 5th mile), Erik was running at a speed of 8 mph
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E