What is the time taken by him to swim to a place 10 km upstream and back ?

Question

A man can swim 3 kmph in still water. If the velocity of stream be 2 kmph .

What is the time taken by him to swim to a place 10 km upstream and back ?

Answer 1

B=velocity of boat=3km/hr ;;;; R=velocity of river=2km/hr ;;;;;;

U=upstream velocity=B-R=1km/hr ;;;;;;; D=downstream velocity=B+R=5km/hr ;;;;;;;;;

Speed=Distance/Time ;;;;;;;;;;;
Time=Distance/speed ;;;;;;;;;;

Given distance =10km

Total time= time upstream +time downstream
= 10/1 + 10/5
= 10 + 2

             ==== 12 hrs