kobel51 wrote: ↑Wed Dec 11, 2013 8:21 am
Chan and Mieko drove separate cars along the entire length of a certain route. If Chan made the trip in 5 minutes, how many minutes did it take Mieko to make the same trip?
1) Mieko's average speed for the trip was 3/4 of Chan's average speed.
2) The route is 14 miles long.
How to simplify the question?
Given: Chan and Mieko drove separate cars along the entire length of a certain route. Chan made the trip in 15 minutes.
Target question: how many minutes did it take Mieko to make the same trip?
Statement 1: Mieko’s average speed for the trip was 3/4 of Chan’s average speed.
If you aren't familiar with attari92's inverse proportion property, you can still solve the question.
Let d = the distance traveled
Let r = Chan's speed (in the miles per minute)
So, (3/4)r = Mieko's speed (in the miles per minute)
In other words,
3r/4 = Mieko's speed
time = distance/speed
So, from the
given information, we can write:
d/r = 15 (minutes)
This means Mieko's travel time = d/(
3r/4)
= (d)(4/3r)
= 4d/3r
= (4/3)(
d/r)
= (4/3)(
15)
= 20
So,
Mieko's travel time is 20 minutes
Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: The route is 14 miles long
Since this statement provides no information about Mieko, there's no way to calculate
Mieko's travel time
Statement 2 is NOT SUFFICIENT
Answer: A
Cheers,
Brent
