SOLUTION: How far upstream can a motorboat travel at 8 mi/hr and still return downstream at 12 mi/hr in a total time of 4 hr?

Question 263749: How far upstream can a motorboat travel at 8 mi/hr and still return downstream at 12 mi/hr in a total time of 4 hr?

Found 2 solutions by mananth, jsmallt9:
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
How far upstream can a motorboat travel at 8 mi/hr and still return downstream at 12 mi/hr in a total time of 4 hr?
let the time taken upstream be x
the down stream time will be 4-x hrs.
speed upstream = 8mph
distance upstream = 8*x
distance down stream = 12*(4-x)
8x= 48-12x
16x=48
x=3 hour---------------------------------- 24 miles
down stream time = 1hour

Answer by jsmallt9(3758) (Show Source): You can put this solution on YOUR website!
There is an error in a solution provided by another tutor. The other solution is correct up to
8x = 48 - 12x
Next we add 12x to each side:
20x = 48 (NOT 16x)
Dividing by 20 we get:
x = 48/20 = 12/5
Since x is the amount of time spent traveling upstream it is not the answer to the question. How far you can travel upstream is miles.
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