Question

A boat covers 50 km in 2 hours downstream and covers the same distance in 5hours upstream. Then find the distance covered in 3 hours in still water?

Answer 1

Let speed of boat = x km/h and that of stream = y km/h

∴speed upstream=x-y km/h and speed downstream = x+y km/h

According to the question,

50 ÷ (x+y) = 2    (∵time=distance÷speed)

x+y = 25 ---------(1)

Also,

50÷ (x-y) = 5

∴ x-y = 10 ------------(2)

Adding equations (1) and (2) ,

x+y+x-y=25+10

2x=35

x=35/2 km/h

(1) ⇒ x+y=25

∴y=25-35/2

   =50-35/2

   =15/2

Now substitute in the required equation