SOLUTION: Meg rowed her boat upstream a distance of 20 miles and then rowed back to the starting point. The total time of the trip was 12 hours. If the rate of the current was 4 mph, find th

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Question 974580: Meg rowed her boat upstream a distance of 20 miles and then rowed back to the starting point. The total time of the trip was 12 hours. If the rate of the current was 4 mph, find the average speed of the boat relative to the water
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39618) (Show Source):
You can put this solution on YOUR website!
Generalization in this data table

_____________________speed___________time___________distance
UPST_________________r-c_____________u______________d
DOWN_________________r+c_____________v______________d
Total________________________________t

Uniform Rates, Travel, RT=D relating rate, time, distance.

The known variables are c, d, t.
Not known either are u and v.

Solve your system for r.

Answer by MathTherapy(10552) (Show Source):
You can put this solution on YOUR website!

Meg rowed her boat upstream a distance of 20 miles and then rowed back to the starting point. The total time of the trip was 12 hours. If the rate of the current was 4 mph, find the average speed of the boat relative to the water

Let average speed in still water be S
Time taken to travel upstream:
Time taken to travel downstream:
We then get:
20(S + 4) + 20(S � 4) = 12(S � 4)(S + 4) ---- Multiplying by LCD, (S � 4)(S + 4)

(S � 6)(3S + 8) = 0
S, or speed of boat in still water = mph