Multiple choice

Raj can row a boat in still water at a speed of m km/hr. It takes him twice the time to row k km upstream than downstream. One day, Raj rows 16 km upstream and 32 km downstream and takes 8 hours, what is the speed of the stream?

  1. 1 km/hr

  2. 2 km/hr

  3. 3 km/hr

  4. 4 km/hr

  5. Can't find
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let boat speed be m and stream speed be s. Upstream speed = m-s, downstream = m+s. Time taken: k/(m-s) = 2 * k/(m+s) -> m+s = 2m-2s -> m = 3s. Given 16/(m-s) + 32/(m+s) = 8. Substitute m=3s: 16/(2s) + 32/(4s) = 8 -> 8/s + 8/s = 8 -> 16/s = 8 -> s = 2.

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