A person walks from his home to his office at 4.5 km/h and reaches 12 minutes late. If he walks at 6 km/h, he reaches 3 minutes early. Find the distance. MCQ with Answer and Explanation
A person walks from his home to his office at 4.5 km/h and reaches 12 minutes late. If he walks at 6 km/h, he reaches 3 minutes early. Find the distance.
A. 4.0 km
B. 4.5 km
C. 5.5 km
D. 5.0 km
Answer: Option B
Solution (By JKSSB Mock Tests)
Time difference = 12 - (-3) = 15 minutes = 15/60 = 0.25 hours. Let distance be d. d / 4.5 - d / 6 = 0.25 => (4d - 3d) / 18 = 0.25 => d / 18 = 0.25 => d = 4.5 km.
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.
Explanation:
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.
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