Two circular tracks T1 and T2 of radii 100 m and 20 m, respectively touch at a point A. Starting from A at the same time, Ram and Rahim are walking on track T1 and track T2 at speeds 15 km/hr and 5 km/hr respectively. The number of full rounds that Ram will make before he meets Rahim again for the first time is
Explanation:
Time taken by Ram to reach the starting point A = 2×π×0.115=π75
Time taken by Rahim to reach the starting point A = 2×π×0.025=π125
Both of them will meet only at A since they are running in different circles which meet at A.
Both of them will reach the starting point after LCMπ75,π125 = π25
∴ Number of rounds completed by Ram when both of them meet again = π25π75 = 3
Hence, (a).
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