Question Number 10069 by Tawakalitu ayo mi last updated on 23/Jan/17

A man can row a boat at 4 km/hr in still water. He row the boat 2km upstream and 2km back to his starting place in 2 hours. How fast is the stream flowing.

Commented byridwan balatif last updated on 23/Jan/17

Commented byTawakalitu ayo mi last updated on 23/Jan/17

God bless you sir.

Answered by sandy_suhendra last updated on 23/Jan/17

let the velocity of the stream=x km/h so the velocity upstream =(4+x) km/h the velocity when he rows back=(4−x) km/h the equation ⇒ (2/(4+x)) + (2/(4−x)) = 2 ((2(4−x)+2(4+x))/((4+x)(4−x))) = 2 ((8−2x+8+2x)/(16−x^2 )) = 2 16−x^2 =8 x^2 = 8 ⇒ x=2(√2) km/h

Commented byTawakalitu ayo mi last updated on 23/Jan/17

God bless you sir.