App Logo

No.1 PSC Learning App

1M+ Downloads
The speed of a boat in still water is 15 km/hr. It can go 30 km upstream and return downstream to the original point in 4 hrs 30 min. The speed of the stream is:

A12 km/hr

B8 km/hr

C5 km/hr

D10 km/hr

Answer:

C. 5 km/hr

Read Explanation:

Explanation: 

D =t[(u2v2)2u]30=t [\frac{(u2-v2)}{2u}] 30

=(412)×[(152v2)2×15]= (4\frac{1}{2})\times{[\frac{(152-v2)}{2\times{15}}]}

=92[(225v2)30]= \frac{9}{2}[\frac{(225-v2)}{30}]

200=225- v2

v2=25

v=5km/hr.


Related Questions:

Speed of a boat in standing water is 12 kmph and the speed of the stream is 3 kmph. A man rows to a place at a distance of 6300 km and comes back to the starting point. The total time taken by him is:
The time taken by the boat can travel 240 km distance along the stream is equal to the time taken by the boat can travel 144 km distance against the stream. The speed of the boat is 20 km/hr. Find the speed of the stream.
A boat goes at a speed of 30 kmph in still water. What time does it take to travel 50 kms upstream and then 70 kms downstream in water of speed 5 kmph?
A motor-boat, travelling at the same speed, can cover 25 km upstream and 39 km downstream in 8 hours. At the same speed, it can travel 35 km upstream and 52 km downstream in 11 hours. The speed of the stream is
If the speed of a boat in still water is 20 km/hr and the speed of the current is 5 km/hr, then the time taken by the boat to travel 100 km with the current is :