Multiple choice

A boat takes double of time taken by it to go downstream while coming in upstream. If speed of water is 3 km/hr. find the speed of boat?

  1. 9 km/hr

  2. 32 km/hr

  3. 8 km/hr

  4. 40 km/hr
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let boat speed = b, water speed = 3 km/hr. Downstream speed = b + 3, upstream speed = b - 3. Given: upstream time = 2 × downstream time. If distance = d, then d/(b-3) = 2d/(b+3). Solving: b + 3 = 2(b - 3), so b + 3 = 2b - 6, giving b = 9 km/hr. Option A is correct.

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