Quantitative Aptitude • Number System & SimplificationMedium
Three bells ring at intervals of 8, 10 and 15 seconds. If they ring together now, after how many seconds will they next ring together?
A. 33 seconds
B. 1,200 seconds
C. 240 seconds
D. 120 seconds✓ Correct Answer
💡 Solution & Explanation
The bells ring together again after a time that is a multiple of all three intervals, and the first such time is the LCM. LCM of 8 and 10 is 40, and LCM of 40 and 15 is 120. So the bells ring together again after 120 seconds. Adding the intervals or multiplying them gives a common time, but not the first one.