Practice NAT Quantitative Reasoning questions with answers and explanations.
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Their closing speed is 20 + 25 = 45 km/h.
Time = 90 ÷ 45 = 2 hours.
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For equal distances, average speed is the harmonic mean 2ab/(a + b).
Thus, 2 × 40 × 60 ÷ 100 = 48 km/h.
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For equal time intervals, average speed is the arithmetic mean.
Thus, (40 + 60)/2 = 50 km/h.
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For opposite directions, relative speeds are added.
Thus, 50 + 70 = 120 km/h.
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For motion in the same direction, relative speed is the difference.
Thus, 80 - 55 = 25 km/h.
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To pass a pole, the train covers its own length.
Speed = 150 ÷ 10 = 15 m/s.
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The train covers its length plus the platform length: 300 meters.
Speed = 300 ÷ 20 = 15 m/s.
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In four days, each works twice.
Completed work is 2/15 + 2/20 = 4/30 + 3/30 = 7/30.
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Total distance is 100 + 140 = 240 meters.
Relative speed is 10 + 14 = 24 m/s, so time = 10 seconds.
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Let B's rate be 1 unit and A's 3 units, total 4 units.
A alone takes 8 × 4/3 = 32/3 days.
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Relative speed is 66 km/h = 55/3 m/s.
Length = speed × time = 55/3 × 18 = 330 meters.
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The machine produces 60/5 = 12 units per hour.
In 8 hours it produces 12 × 8 = 96 units.
