SOLUTION: Maria jogs 15 miles and bicycles back. The total trip requires 3 hours. If she bicycles twice as fast as she jogs, how fast does she bicycle?

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Question 178796: Maria jogs 15 miles and bicycles back. The total trip requires 3 hours. If she bicycles twice as fast as she jogs, how fast does she bicycle?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Maria jogs 15 miles and bicycles back. The total trip requires 3 hours.
If she bicycles twice as fast as she jogs, how fast does she bicycle?
:
Let s = jogging speed
then
2s = biking speed
:
Write a time equation; time = dist%2Fspeed
:
time jogging + time riding = 3 hrs
15%2Fs + 15%2F%282s%29 = 3
multiply equation by 2s
:
2s*15%2Fs + 2s*15%2F%282s%29 = 2s(3)
cancel out the denominators
2(15) + 15 = 6s
:
30 + 15 = 6s
:
45 = 6s
s = 45%2F6
s = 7.5 mph is the jogging speed
then
2(7.5) = 15 mph is the biking speed
;
:
Check solution by finding the times
15/7.5 = 2 hr
15/15 = 1 hr
------------
total = 3 hrs. confirms our solution