Problema Solution
A motorboat heads upstream on a river that has a current of 3 miles per hour. The trip upstream takes 5 hours, and the return trip takes 2.5 hours. What is the speed of the motorboat? (Assume that the motorboat maintains a constant speed relative to the water.)
Answer provided by our tutors
let 'x' represent the speed of the motorboat in mph, then 'x+3' represents the speed downstream and 'x-3' represents the speed upstream
distance = speed * time
both trips cover the same distance, so we set their 'speed*time' expressions equal to each other:
(x+3)2.5 = (x-3)5
solving for 'x' we have x=9
the speed of the motorboat is 9 mph