Question

A boat covers a certain distance downstream in 5 hours and it covers the same distance upstream in 6 hours .

if the speed of the water is 2 km/h . Find the speed of the boat in still water.​

Answer 1

Let speed of boat - x

Let speed of stream - y

Distance = speed × time

Time taken for downstream is 5 hrs.

Speed of boat in downstream = x + 2  

Speed = (x+2) × 5   -   (i)

Time taken for upstream is 6 hrs.

Speed of boat in upstream is  = x - 2

Speed = (x−2) × 6   -   (ii)

Solving equations (i) and (ii)

Speed = (5x+10) = (6x−12)

⇒ 5x + 10 = 6x − 12

⇒ 6x - 5x = 10 + 12

⇒ x = 22

∴ Speed of boat in still water is 22 km/hr