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Q1 LCM HCF

Three wheels can complete 60, 36 and 24 revolutions per minute. There is a red spot on each wheel that touches the ground at time zero. After how much time, all these spots will simultaneously touch the ground again?

(a) 5/2 s

(b). 5/3 s

(c). 5 s

(d). 7.5 s

Three wheels can complete 60, 36, 24 revolutions per minute.
Three wheels can complete 1, 0.6, 0.4 revolutions per second.
Time to complete one revolution - 1, 5/3, 5/2 secs.
LCM of 1, 5/3 and 5/2 is 5.
After 5 mins, all these spots will simultaneously touch the ground again

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