SOLUTION: A motor boat travels 3 times as fast as the current. A trip up the river and back takes 10 hr, and the total distance of the trip is 100 km. Find the speed of the current.

Question 693511: A motor boat travels 3 times as fast as the current. A trip up the river and back takes 10 hr, and the total distance of the trip is
100 km. Find the speed of the current.
Answer by checkley79(3341) (Show Source): You can put this solution on YOUR website!
D=RT
50=(3X-X)T UP STREAM.
T=50/(2X)
50=(3X+X)T DOWN STREAM.
T=50/(4X)
ADD THE 2 T EQUATIONS & SOLVE FOR X.
50/(2X)+50/(4X)=10
(50*2+50)/4X=10
(100+50)/4X=10
150/4X=10
4X*10=150
40X=150
X=150/40
X=3.75 KPH. IS THE SPEED OF THE CURRENT.
3*3.75=11.25 KPH. IS THE SPEED OF THE BOAT.
PROOF:
50/2*3.75+50/4*3.75=10
50/7.5+50/15=10
6.67+3.33=10
10=10
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