Speed of motorboat in still water is 35 kmph. If the motorboat travels 100 km along the stream in 2 hour 30 min, then the time taken by it to cover the same distance against the stream is-

Question: Speed of motorboat in still water is 35 kmph. If the motorboat travels 100 km along the stream in 2 hour 30 min, then the time taken by it to cover the same distance against the stream is-

Solution:
The speed of the motorboat in still water is 35 km/hr.
let the speed of the stream = x km/hr
Downstream speed = Distance/time
= 100/2.5
= 40 km/hr

Speed of stream = 35 + x = 40
∴ x = 5 km/hr

Upstream speed = 35 - 5 = 30 km/hr
Time taken in upstream = 100/30 = 3 hour 20 min