Multiple choice

A man can row a boat at a speed of 8 km/hr in still water. If the velocity of the current is 2 km/hr and he takes 1 hour to row to a place and come back, then how far is the place?

  1. 6 km

  2. 4.25 km

  3. 5.26 km

  4. 3.75 km

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

Speed downstream = 8+2 = 10 km/hr. Speed upstream = 8-2 = 6 km/hr. Let distance be d. d/10 + d/6 = 1. (3d + 5d) / 30 = 1. 8d = 30. d = 3.75 km.

AI explanation

The downstream speed is the sum of the speed of the boat in still water and the speed of the current, which is 8 + 2 = 10 km/hr. The upstream speed is the difference between the speed of the boat and the current, which is 8 - 2 = 6 km/hr. Let the distance to the place be d kilometers; the total time for the round trip is d/10 + d/6 = 1 hour. Multiplying by 30 gives 3d + 5d = 30, so 8d = 30 and d = 3.75 km.

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