Question

Ratio of downstream speed to upstream speed of a boat is 11 : 5. By what percentage speed of stream is less than boat’s speed?
1. 62.5
2. 37.5
3. 50
4. 60
5. 33.33

Answer 1

Correct Answer - Option 1 : 62.5

Given:-

Ratio of downstream speed to upstream speed = 11/5

Formula:-

Boat speed = ½ (D + U)

Stream speed = ½ (D - U)

Where D and U are downstream and upstream speeds respectively.

Calculation:-

Let U be 11x and D be 5x as ratio is 11/5

Boat speed = ½ (11x + 5x) = 8x

Stream speed = ½ (11x - 5x) = 3x

Required percentage = {(8x – 3x)/8x} × 100 = 62.5%