SOLUTION: From a point on a lake, two boats are driven in opposite directions, one at 9 mph and the other at 10 mph. In how many hours will they be 57 minutes apart?

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Question 627413: From a point on a lake, two boats are driven in opposite directions, one at 9 mph and the other at 10 mph. In how many hours will they be 57 minutes apart?
Found 2 solutions by Alan3354, hammy:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
From a point on a lake, two boats are driven in opposite directions, one at 9 mph and the other at 10 mph. In how many hours will they be 57 minutes apart?
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Going in opposite directions, speeds are added.
--> 19 mi/hr
=================
d = r*t
t = d/r

Answer by hammy(9) About Me  (Show Source):
You can put this solution on YOUR website!
d=rt
t=d/r
So, the boat that travels 9mph will travel .15 miles per minute.
9%2F1%2A1%2F60=9%2F60=.15
The boat that travels 10mph will travel .16 miles per minute.
10%2F1%2A1%2F60=1%2F6=.16
So, in order to get 57 minutes, we must take each boat's time from the origin and add those times.
T%281%29%2BT%282%29=57
T=D%2FR
D%281%29%2FR%281%29%2BD%282%29%2FR%282%29=57
R(1)=.15 miles per minute
R(2)=.16 miles per minute
D%281%29%2F.15%2BD%282%29%2F.16=57
.16%2AD%281%29%2B.15%2AD%282%29=1.368
D%281%29=.15%2AT
D%282%29=.16%2AT
.16%2A.15%2AT%2B.15%2A.16%2AT=1.368
.048%2AT=1.368
T=28.5 minutes
But we want hours, so .475 hours