Multiple choice

Directions: Study the given information carefully to answer the question that follows: The speeds of Boat A and Boat B are in the ratio 4 : 5. The speed of the current with respect to Boat A is 1/4th and with respect to Boat B is 1/5th. If the distances covered by Boat A and Boat B are the same while going upstream and downstream respectively, then the ratio of times taken by Boat A and Boat B is

  1. 1 : 2

  2. 1 : 3

  3. 2 : 1

  4. 2 : 3

  5. 2 : 5
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let speeds be 4v and 5v. Current speed for A is v (1/4 of 4v) and for B is v (1/5 of 5v). Downstream speed for B = 5v + v = 6v. Upstream speed for A = 4v - v = 3v. Distance = Speed * Time. Since distances are equal, 3v * Ta = 6v * Tb, so Ta/Tb = 6/3 = 2/1.

AI explanation

Since the ratio of the speeds of Boat A and Boat B is 4 to 5, let the speed of Boat A be 4x and the speed of Boat B be 5x. The current is 1/4th the speed of Boat A, making the stream speed x, which conveniently is also 1/5th the speed of Boat B. Boat A travels upstream at a speed of 4x - x = 3x, and Boat B travels downstream at a speed of 5x + x = 6x. For the same distance D, the time taken by Boat A is D/3x and the time taken by Boat B is D/6x. The ratio of their times is (D/3x) / (D/6x), which equals 2 to 1.

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