The speed of a boat in still water is thrice the speed of the stream. If the boat takes 15.5 sec to go to a certain place downstream, then find the additional time required to cover the same distance travelling upstream.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 15.5 Second.
Let's assume,
The speed of a boat in still water = 3x
Speed of stream = x
Distance = D
According to the question,
D/(x + 3x) = 15.5 Sec
⇒ D = 62x
The total time required to cover the same distance travelling upstream = D/(3x - x)
= 62x/2x = 31 Sec
Additional time = 31 - 15.5 = 15.5 Sec