Question

A tortoise takes twice as long to travel a distance against the stream as to flow the same distance in favour of the stream. The ratio of the speed of the tortoise (in still water) and the stream is:

• A. 2:1
• B. 1:2
• C. 3:1
• D. 1:3

Answer 1

The correct option is C 3:1

Let speed upstream = U

And the speed downstream = D = 2U (given)

Speed in still water = (U + D) /2
= (U + 2U) /2 = 3U/2

Speed of the stream = (D – U)/2
= (2U – U)/2 = U/2

Speed in still water : Speed of the stream $\to$ 3U/2 : U/2 = 3:1