NIELIT 2017 July Scientist B - Section A: 4

Question

A boatman goes $2$ km against the current of the stream in $1$ hour and goes $1$ km along the current in $10$ minutes. How long will it take to go $5$ km in stationary water?

• A. $40$ minutes
• B. $1$ hour
• C. $1$ hr $15$ min
• D. $1$ hr $30$ min

Answer 1

let s = boatman’s speed in still water , r = river’s flow(speed)

s+r = 2 kmph (speed = distance/time)

s-r = 6 kmph(convert time given in minutes into hour)

thus , s=4kmph

hence, time = 5/4 hrs = 1.25 hr = 1 hour 15 minutes