SOLUTION: If a boat goes downstream 72 miles in 3 hours and upstream 60 miles in 6 hours, the rate of the river and the rate of the boat in still water respectively are?
Question 203118: If a boat goes downstream 72 miles in 3 hours and upstream 60 miles in 6 hours, the rate of the river and the rate of the boat in still water respectively are? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! If a boat goes downstream 72 miles in 3 hours and upstream 60 miles in 6 hours,
the rate of the river and the rate of the boat in still water respectively are?
:
Let x = the rate of the boat
Let y = the rate of the current
then
(x+y) = boat speed downstream
(x-y) = boat speed upstream
:
Write two distance equations: dist = time * speed
:
3(x + y) = 72
6(x - y) = 60
:
Simplify both equations, divide the 1st by 3, and the 2nd by 6: results:
x + y = 24
x - y = 10
-------------addition eliminates y, find x:
2x = 34
x =
x = 17 mph boat speed in still water
and
17 + y = 24
y = 24 - 17
y = 7 mph is the current speed
:
:
Check solution in the 1st equation
3(17 + 7) = 24
2(24) = 72
