Q. The speed of a boat in still water is 10 km/hr. It covers (upstream) a distance of 45 km in 6 hours. The speed (in km/hr) of the stream is:
Answer:
2.5 kmph
Notes: Upstream speed of boat = $ \frac{Distance}{Time}=\frac{45}{6}=\frac{15}{2}$
=7.5 kmph
Speed Of Current = 10-7.5 = 2.5 kmph
Hence option [D] is the right answer.