Speed of a boat in still water is 12 kmph and the speed of the stream is x kmph. If in travelling 270 km upstream boat takes 66⅔% more time than travelling 270 km downstream, find the value of x.

Explanation

Given: Total distance covered = 270 km. Speed of Boat in still water = 12 km/hr. Speed of stream = x km/hr. Travelling Upstream takes 200/3% more. Concept used: Upstream speed = Speed of boat – Speed of stream; Downstream speed = Speed of Boat + Speed of stream. Calculation: Upstream speed = (12 – x) km/hr; Downstream speed = (12 + x) km/hr. So, 270/(12 – x) = 270/(12 + x) × (100 + 200/3)% ⇒ 8x = 24 ⇒ x = 3. ∴ The speed of the stream is 3 km/hr.