While on a straight road, car X and car Y are traveling at different constant rates. If car X is now 1 mile ahead of car Y, how many minutes from now will car X be 2 miles ahead of car Y?
(1) Car X is traveling at 50 miles per hour and car Y is traveling at 40 miles per hour.
(2) 3 minutes ago car X was 1/2 mile ahead of car Y.
Target question:
How many minutes from now will car X be 2 miles ahead of car Y?
Given: Car X is now 1 mile ahead of car Y
Statement 1: Car X is traveling at 50 miles per hour and car Y is traveling at 40 miles per hour.
Notice that we could easily duplicate this scenario in real life.
Start with Car X 1 mile ahead of car Y (given info)
Have Car X drive at 50 mph and car Y at 40mph.
Use a stopwatch to time how long it takes for Car X to be 2 miles ahead of Y.
As you can see, we have enough information to answer the
target question
Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2:
3 minutes ago car X was 1/2 mile ahead of car Y.
If car X is
presently 1 mile ahead, we can see that car X gains 1/2 mile every 3 minutes.
At that rate,
car X will gain another 1 mile in 6 minutes.
Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer =
D
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
