Question 889394: Ryan drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took 12 hours. When Ryan drove home, there was no traffic and the trip only took 8 hours. If his average rate was 20 miles per hour faster on the trip home, how far away does Ryan live from the mountains?
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! Ryan drove to the mountains last weekend.
There was heavy traffic on the way there, and the trip took 12 hours.
When Ryan drove home, there was no traffic and the trip only took 8 hours.
If his average rate was 20 miles per hour faster on the trip home, how far away does Ryan live from the mountains?
:
Let s = his speed in traffic
then
(s+20) = his no-traffic speed
:
The distance, there and back is the same. Write a dist equation; dist = time * speed
12s = 8(s+20)
12s = 8s + 160
12s - 8s = 160
4s = 160
s = 160/4
s = 40 mph in heavy traffic
:
Find the distance
12 * 40 = 480 mi to the mountains
:
Check the dist on the return trip (20 mph faster)
8 * 60 = 480 mi, the same
|
|
|
