A person row a boat 12 km downstream in 1 hour. If the river current flows at 3 km/h, find the time taken by the boat to row the same distance upstream. MCQ with Answer and Explanation
A person row a boat 12 km downstream in 1 hour. If the river current flows at 3 km/h, find the time taken by the boat to row the same distance upstream.
A. 3.0 hours
B. 1.5 hours
C. 2.0 hours
D. 2.5 hours
Answer: Option C
Solution (By JKSSB Mock Tests)
Downstream speed = 12 / 1 = 12 km/h. Baseline boat speed in still water = Downstream speed - Current speed = 12 - 3 = 9 km/h. Upstream speed = Still water speed - Current speed = 9 - 3 = 6 km/h. Time taken upstream = Distance / Upstream speed = 12 / 6 = 2 hours.
Excluding operational station stops, a city bus routes at an average of 42 km/h, and including stops its net average speed is 35 km/h. For how many minutes does it stop per hour?
A car covers a distance from town X to town Y at a speed of 45 km/h and returns at a speed of 75 km/h. If the total journey takes 8 hours, find the one-way distance between the two towns.
Explanation:
Let the one-way distance be d km. Time taken forward = d/45 and return = d/75. Given: d/45 + d/75 = 8. (5d + 3d) / 225 = 8 => 8d / 225 = 8 => d = 225 km.
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