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, so b - c = 10/3. Downstream: speed = 18/4 = 9/2 kmph, so b + c = 9/2. Solving: b = 47/12 kmph (boat in still water), c = 7/12 kmph (current). The question only asks for current speed, which is 7/12 kmph.

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