SOLUTION: Karen traveled 640 miles by boat and returned by plane. She spent 42 hours traveling on the trip. If the rate of the plane is 20 times faster than the rate of the boat, find each r

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Question 635043: Karen traveled 640 miles by boat and returned by plane. She spent 42 hours traveling on the trip. If the rate of the plane is 20 times faster than the rate of the boat, find each rate.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Karen traveled 640 miles by boat and returned by plane.
She spent 42 hours traveling on the trip.
If the rate of the plane is 20 times faster than the rate of the boat, find each rate.
:
Let r = speed of the boat
then
20r = speed of the plane
:
Write a time equation; time = dist/speed
:
boat time + plane time = 42 hrs
640%2Fr + 640%2F%2820r%29 = 42
reduce the fraction, divide 20 into 640
640%2Fr + 32%2Fr = 42
672%2Fr = 42
42r = 672
r = 672/42
r = 16 mph, boat speed
then
20(16) = 320 mph is the plane speed
:
:
Confirm this find the travel time of each
640/16 = 40 hrs
640/320 = 2 hrs
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totals: 42 hrs