Asked Oct 1, 2019

A boat in a river travels downstream between 2 points, 50miles apart, in 1 hour. The return trip against the current takes 2.5 hours. What is the boats speed (in still water) ? 


Expert Answer

Step 1

For the boat's first trip, i.e. the boat travelling downstream will have the speed of the current added to the speed of the boat. This is because the current and the boat are moving in the same direction.

For the return trip, the speed of the current will be subtracted from the speed of the boat as the direction is different.

To Find: Speed of boat in still water.

Step 2

The conditions given in the question can be put in equation as below:


Image Transcriptionclose

So, for the first trip the distance covered is 50 miles and the time taken is 1 hour, we get the equation as, Distance d Vboat Vcurrent Speed Time 50miles 50 mi/h.... () Vboat Vcurrent 1 hour And, for the return trip the time taken is 2.5 hour, the equation will be written as: 50miles 20 mi/h.... (2) Vboat Vcurrent 2.5 hour

Step 3

Adding equations (...


Image Transcriptionclose

Vboat varrent Vboat = 70 current 2Vboat 70 35 mi/h Vboat


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