BTGmoderatorDC wrote: ↑

Tue Jul 07, 2020 8:27 pm

Two racecar drivers, Abernathy and Berdoff, are driving around a circular track. If Abernathy is 200 meters behind Berdoff and both drivers drive at their respective constant rates, how long, in seconds, will it take for Abernathy to catch up to Berdoff?

(1) The circumference of the racetrack is 1,400 meters.
(2) Abernathy is driving 25 meters per minute faster than Berdoff.


OA B

Source: Manhattan Prep

Target question: How long, in seconds, will it take for Abernathy to catch up to Berdoff?

Given: Abernathy is 200 meters behind Berdoff

Statement 1: The circumference of the racetrack is 1,400 meters.
The circumference of the racetrack is irrelevant here. What matters is their respective speeds.
For example, it could be that Abernathy and Berdoff are driving at the same speed, so Abernathy will NEVER catch up to Berdoff.
Or it could be the case that Abernathy's speed is 200 meters/second FASTER THAN Berdoff's speed, in which case, Abernathy will catch up to Berdoff in 1 second.
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: Abernathy is driving 25 meters per minute faster than Berdoff
If Abernathy is driving 25 meters per minute faster than Berdoff, then the GAP between Abernathy and Berdoff will DECREASE by 25 meters EVERY MINUTE.
There is currently as 200-meter gap
So, it will take 8 minutes to decrease the gap from 200 meters to 0 meters.
In other words, Abernathy will catch up to Berdoff in 8 minutes.
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

Cheers,
Brent