Four bells begin to toll together respectively at the intervals of 8, 10, 12 and 16 seconds. After how many seconds will they toll together again?
Correct answer: C. 240 seconds
- A. 246 seconds
- B. 242 seconds
- C. 240 seconds
- D. 243 seconds
Explanation
The bells toll together after the LCM of their intervals: LCM(8, 10, 12, 16) = 2^4 x 3 x 5 = 240 seconds. Therefore they meet again after 240 seconds. The likely mistake is 242 seconds, obtained by adding intervals instead of finding their LCM.
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