Places A and B are 144 km apart. Two cars start simultaneously, one from A and the other from B. If they move in the same direction, they meet after 12 hours, but if they move towards each other they meet after 9/8 hours. The speed (in km/h) of the car moving at a faster speed, is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e 70.
| Understanding/Application |
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Speed of faster car = V Speed of slower car = v Case 1 - When cars travel in the same direction. Distance = 144 km T = 12 hours Relative speed = V - v V - v = 144/12 = 12 ....(1 |
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Case 2 - When cars travel in the opposite direction. Distance = 144 km Time = 9/8 hours Relative speed = V + v V + v = 144(8)/9 = 128 .....(2 Subtracting eq 1 and 2, we get - 2V = 12 + 128 2V = 140 V = 70 km/hr |