The speed of a boat in still water is 15 km/h and the speed of the current is one-third the speed of the boat in still water. How much time will it ta - Quantitative Aptitude MCQ Competitive Exam 2026 | ExamTest.live

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The speed of a boat in still water is 15 km/h and the speed of the current is one-third the speed of the boat in still water. How much time will it take to go 24 km upstream and 20 km downstream, assuming that no time is lost in changing direction?

Solution & Step-by-step Explanation

Given:Speed of the boat in still water (u) = 15 km/h Speed of the current (v) = \frac{1}{3} \times 15 = 5 km/h Downstream speed (D) = u + v = 15 + 5 = 20 km/h Upstream speed (U) = u - v = 15 - 5 = 10 km/h Total time taken = Time taken upstream + Time taken downstream Total Time = \frac{Upstream Distance}{U} + \frac{Downstream Distance}{D} Total Time = \frac{24}{10} + \frac{20}{20} = 2.4 + 1 = 3.4 hours Converting 0.4 hours into minutes: 0.4 \times 60 = 24 minutes So, total time = 3 hours 24 minutes.

Try it yourself before checking the explanation above.

The speed of a boat in still water is 15 km/h and the speed of the current is one-third the speed of the boat in still water. How much time will it take to go 24 km upstream and 20 km downstream, assuming that no time is lost in changing direction?

3 hours 20 minutes

3 hours

3 hours 24 minutes

3 \frac{1}{2} hours

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