A car climbs a hill at 24 km/h and descends the same hill at 36 km/h. Find the average speed of the car for the entire journey. MCQ with Answer and Explanation
The speeds of two parallel running trains are in the ratio 5 : 4. Moving in opposite directions, they take 6 seconds each to pass a stationary signal post. Find the total time they take to cross each other completely.
Explanation:
Let the speeds be 5x and 4x. Length of first train = 5x * 6 = 30x. Length of second train = 4x * 6 = 24x. Total passing distance = 30x + 24x = 54x. Relative speed = 5x + 4x = 9x. Time taken to cross each other = 54x / 9x = 6 seconds.
A thief is spotted by a policeman from a distance of 150 meters. The thief runs at 11 km/h and the policeman chases him at 12 km/h. Find the distance covered by the thief before he is caught.
Explanation:
Relative speed = 12 - 11 = 1 km/h. Time to catch the thief = 0.15 km / 1 km/h = 0.15 hours. Distance covered by thief = Speed * Time = 11 km/h * 0.15 hours = 1.65 km = 1650 meters.
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