Practice Pakistan questions with answers and explanations.
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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.
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Downstream speed equals still-water speed plus stream speed.
Thus, 12 + 3 = 15 km/h.
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If 40% takes 12 days, 10% takes 3 days.
The remaining 60% takes 18 days.
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Upstream speed equals still-water speed minus stream speed.
Thus, 10 - 2 = 8 km/h.
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The leak rate is 1/9 - 1/12 = 1/36 tank per hour.
Thus, the leak alone empties the tank in 36 hours.
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Downstream speed is 15 km/h and upstream speed is 10 km/h.
Still-water speed is their average: 12.5 km/h.
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Speed equals distance divided by time.
Thus, 180 ÷ 3 = 60 km/h.
