Question

A motorboat goes downwards and covers the distance between two ports in 5 hours and return back in 7 hours. If the water is fllowing at 2km/h, find the speed of the boat in still water.

Answer 1

let distance be x

x

speed of upstream = x/5

and downstream = x/4  

speed of stream = 3 km/hr

speed of boat = y.

y + 3= x/4  

y - 3 = x/5  

from here  

4y+12=5y-15

y=27  

y= 27 km/hr = boat of speed