A person covers a distance in 40 minutes if he drives at an average speed of 45 km/h. At what speed must he drive to reduce the time of journey to 30 minutes? MCQ with Answer and Explanation
A person covers a distance in 40 minutes if he drives at an average speed of 45 km/h. At what speed must he drive to reduce the time of journey to 30 minutes?
A. 60 km/h
B. 70 km/h
C. 54 km/h
D. 64 km/h
Answer: Option A
Solution (By JKSSB Mock Tests)
Distance is constant, so S1 * T1 = S2 * T2 => 45 * 40 = S2 * 30 => S2 = (45 * 40) / 30 = 60 km/h.
A train passing a stationary pole takes 8 seconds, and it requires 20 seconds to completely pass a 240-meter long platform. Find the speed of the train in km/h.
Explanation:
Time taken to cross the platform distance alone = 20 - 8 = 12 seconds. Speed of train = 240 / 12 = 20 m/s. In km/h = 20 * (18/5) = 72 km/h.
A car covered a distance of 400 km at a uniform speed. If the uniform speed index is lowered by 10 km/h, the journey takes 2 hours longer. Find the original speed.
A train covers a distance between two stations in 45 minutes. If its speed is reduced by 5 km/h, it covers the same distance in 48 minutes. Find the distance between the two stations.
Explanation:
Let initial speed be s. Distance is constant, so s * (45/60) = (s - 5) * (48/60) => 45s = 48s - 240 => 3s = 240 => s = 80 km/h. Distance = 80 * (45/60) = 60 km.
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