Problema Solution
A tourist boat is used for sightseeing in a nearby river. The boat travels 2.4 miles downstream and in the same amount of time, it travels 1.8 miles upstream. If the boat travels at an average speed of 21 miles per hour in the still water, find the current of the river.
Answer provided by our tutors
let
v = 21 mph the average speed of the boat in still water
d1 = 2.4 mi the distance traveled downstream
d2 = 1.8 mi the distance traveled upstream
c = the current of the river, c>0
the speed of the boat traveling downstream is: v + c
the speed of the boat traveling upstream is: v - c
since speed = distance/time follows time = distance/speed
since the boat travels the same amount of time upstream and downstream we have:
d1/(v + c) = d2/(v - c)
2.4/(21 + c) = 1.8/(21 - c)
by solving the above equation we find:
c = 3 mph
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the current of the river is 3 mph.