The speed of boat A in still water is 4 times the speed of stream and covers 24 km upstream in 8 hours. If the speed of boat B in still water is 2 kmph more than the speed of boat A in downstream, then find the time (in minutes) taken by boat B to cover the same distance in upstream.

Correct option is C

Let the speed of stream be x kmph.
So, Speed of boat A in still water=4×x=4x kmph
ATQ,
24/(4x-x)=8
x=1
So, speed of stream=x=1 kmph
Speed of boat B in still water=5x+2=5×1+2=7 kmph
Required time=24/(7-1)=4 hours=4×60=240 minutes