Question

Bhanu can row upstream at 8 kmph and downstream at 15 kmph. Find Bhanu's rowing speed in still water and the speed of current respectively.

1. 11.5 kmph, 3.5 kmph
2. 3.5 kmph, 11.5 kmph
3. 12 kmph, 3 kmph
4. 3 kmph, 12 kmph

Answer 1

Correct Answer - Option 1 : 11.5 kmph, 3.5 kmph

Given:

Downstream speed = d = 15 kmph

Upstream speed = u = 8 kmph

Formula used:

Speed of boat in still water = (d + u)/2

Speed of stream = (d – u)/2

Calculations:

Let the speed of boat in still water be B and the speed of stream be S

Speed of boat in still water

⇒ B = (15 + 8)/2

⇒ B = 23/2

⇒ B = 11.5 kmph

Speed of stream

⇒ S = (15 – 8)/2

⇒ S = 7/2

⇒ S = 3.5 kmph

∴ The speed of boat in still water is 11.5 kmph and the speed of stream is 3.5 kmph