Multiple choice

A boat takes 15 hours to travel downstream from point X to point Y and comes back to point X upstream. If the speed of the boat in still water is 10 kmph and the speed of the stream is 6 kmph, what is the distance between X and Y?

  1. 80 m

  2. 48 km

  3. 48 m

  4. 80 km

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let d be the distance. Downstream speed is 10+6=16 kmph, upstream is 10-6=4 kmph. Total time is d/16 + d/4 = 15. Solving gives 5d/16 = 15, so d = 48 km.

AI explanation

Using the downstream and upstream speed formulas, the downstream speed is 10 plus 6, giving 16 kmph, and the upstream speed is 10 minus 6, giving 4 kmph. Let the distance be D; using the Time formula, the total time is (D divided by 16) plus (D divided by 4). Setting this equal to 15 hours gives (D divided by 16) plus (4D divided by 16) equals 15, so 5D divided by 16 equals 15. Solving for D gives D equals 48; the distance between X and Y is 48 km.

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