SOLUTION: Marco�s speed riding up a hill is 40% of his speed riding down the hill. It takes him two hours longer to ride up the hill than it takes him to ride down the hill. How long, in hou

Question 316801: Marco�s speed riding up a hill is 40% of his speed riding down the hill. It takes him two hours longer to ride up the hill than it takes him to ride down the hill. How long, in hours, does it take him to ride down the hill? Express your answer as a common fraction.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Marco�s speed riding up a hill is 40% of his speed riding down the hill.
It takes him two hours longer to ride up the hill than it takes him to ride down the hill.
How long, in hours, does it take him to ride down the hill?
Express your answer as a common fraction.
:
Let s = his speed down hill
then
.4s = his speed up hill
:
Let one way distance = 10
:
Write a time equation: time = dist/speed
:
Time up - time down = 2 hrs
- = 2 hrs
multiply by .4s, results
10 - .4(10) = 2(.4s)
:
10 - 4 = .8s
:
6 = .8s
s =
s = 7.5 is the downhill speed
then
.4(7.5) = 3 is the uphill speed
:
Find the time to ride down hill
10/7.5 = 1 hr
:
Check solution by finding the time uphill
10/3 = 3 hr, a two hr difference
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