Six bells start together and toll at intervals of 2, 4, 6, 8, 10, and 12 seconds respectively. In 30 minutes, how many times do they toll together?
Aptitude
Problems on H.C.F and L.C.M
Difficulty: Easy
Choose an option
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A15
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B16
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C30
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D31
Answer
Correct Answer: 16
Explanation
Concept / Approach
- They toll together every LCM of the given intervals.
Step-by-step calculationLCM(2,4,6,8,10,12) = 120 seconds30 minutes = 1800 secondsNumber of meetings = (1800 ÷ 120) + 1 = 15 + 1 = 16
Why +1?They also toll together at time t = 0 (the very start). Since 1800 is a multiple of 120, the final instant is also included.
Final Answer16