Multiple choice general knowledge math & puzzles

A boat travels 20 kms upstream in 6 hrs and 18 kms downstream in 4 hrs.Find the speed of the boat in still water and the speed of the water current?

  1. 1/2 kmph

  2. 7/12 kmph

  3. 5 kmph

  4. none of these

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Upstream speed = 20/6 = 10/3 kmph. Downstream speed = 18/4 = 4.5 kmph. Speed in still water = (4.5 + 3.33)/2 = 3.91 kmph. Speed of current = (4.5 - 3.33)/2 = 0.583 (7/12) kmph.