Speed, time and distance
Ten quantitative aptitude questions, each marked as you answer.
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A scooter runs at 54 km/h. What is its speed in metres per second?
Answer and working
Answer B
Multiply by 5/18: 54 × 5/18 = 15 m/s.
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A train 340 m long crosses a platform 410 m long in 30 seconds. What is the speed of the train?
Answer and working
Answer B
It must cover its own length and the platform: 340 + 410 = 750 m in 30 s, so 25 m/s = 25 × 18/5 = 90 km/h.
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A bus goes from Pune to Nashik at 10 km/h and returns by the same road at 30 km/h. What is its average speed for the whole journey?
Answer and working
Answer B
For equal distances, average speed = 2xy/(x + y) = 2 × 10 × 30 ÷ 40 = 15 km/h. The plain average, 20, ignores that the slower leg takes longer.
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A scooter runs at 144 km/h. What is its speed in metres per second?
Answer and working
Answer C
Multiply by 5/18: 144 × 5/18 = 40 m/s.
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A train 230 m long passes a signal post in 23 seconds. What is its speed in km/h?
Answer and working
Answer B
Speed = 230 ÷ 23 = 10 m/s = 10 × 18/5 = 36 km/h.
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A bus goes from Pune to Nashik at 48 km/h and returns by the same road at 80 km/h. What is its average speed for the whole journey?
Answer and working
Answer A
For equal distances, average speed = 2xy/(x + y) = 2 × 48 × 80 ÷ 128 = 60 km/h. The plain average, 64, ignores that the slower leg takes longer.
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A scooter runs at 54 km/h. What is its speed in metres per second?
Answer and working
Answer D
Multiply by 5/18: 54 × 5/18 = 15 m/s.
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A train 310 m long crosses a platform 540 m long in 85 seconds. What is the speed of the train?
Answer and working
Answer D
It must cover its own length and the platform: 310 + 540 = 850 m in 85 s, so 10 m/s = 10 × 18/5 = 36 km/h.
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Two trains 260 m and 220 m long run on parallel tracks in opposite directions at 58 km/h and 50 km/h. How long do they take to cross each other?
Answer and working
Answer D
Relative speed = 58 + 50 = 108 km/h = 30 m/s. Distance = 260 + 220 = 480 m. Time = 480 ÷ 30 = 16 seconds.
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A train 170 m long crosses a platform 550 m long in 24 seconds. What is the speed of the train?
Answer and working
Answer A
It must cover its own length and the platform: 170 + 550 = 720 m in 24 s, so 30 m/s = 30 × 18/5 = 108 km/h.
More quantitative aptitude: Percentages, Profit, loss and discount, Simple interest, Compound interest, Ratio and proportion, Averages.