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
AI explanation

Upstream speed = 20 km / 6 hr = 10/3 kmph, and downstream speed = 18 km / 4 hr = 9/2 kmph. The current's speed is half the difference between downstream and upstream speeds: (9/2 - 10/3)/2 = (7/6)/2 = 7/12 kmph, which is the option marked correct (the boat's own still-water speed would instead be the average of the two, about 47/12 kmph).

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