Carcass wrote:
Rachel and Rob live 190 miles apart. They both drive in a straight line toward each other to meet for tea. If Rachel drives at 50 mph and Rob drives at 70 mph, then how many miles apart are they exactly 45 minutes before they meet?
A. 50
B. 60
C. 70
D. 90
E. 100
Kudos for the right answer and explanation
This is a
shrinking gap question
So, the rate at which the gap shrinks = 50 mph + 70 mph =
120 mph
The question asks us to find their distance apart exactly 45 minutes
BEFORE they meet.
When they meet, they are ZERO miles apart.
So let's work backwards from the time they meet.
distance = (rate)(time)Note: Since the speed is given in miles per hour HOUR, we must convert 45 minutes to
3/4 hours
So, 45 minutes BEFORE they meet, the distance between them = (
120)(
3/4) = 90 miles
Answer: D
Cheers,
Brent