Question

Four bells ring simultaneously at starting and an interval of 6 sec, 12 sec, 15 sec and 20 sec respectively. How many times they ring together in 2 hours?

• A. 120
• B. 60
• C. 121
• D. 112

Answer 1

Answer:

C. 121

LCM of (6, 12, 15, 20) = 60 All 4 bells ring together again after every 60 seconds In 2 Hours, they ring together = [(2 × 60 × 60)/60] times + 1 (at the starting) = 121 times