Question

A motorboat whose speed in still water is 15 kilometre per hour goes 30 km downstream and comes back in a total 4 hour 30 minutes. Determine the speed of the stream​

Answer 1

Let the speed of the stream be x km/hr. Then,

Speed downstream = (15 + x) km/hr,

Speed upstream = (15 - x) km/hr.

Therefore,

30/(15+x) + 30/(15-x) = 4(1/2)

=> 900/(225-x^2) = 9/2

=> 9x^2 = 225

=> x^2 = 25

=> x = 5

Hope this helps

Answer 2

Answer:

The speed of the stream should be 9 km/hr...