There are four table clocks. They ring every 10 min , 15 min , 20 min and 25 min respectively. If they all ring together at 10 a.m., then at what time will they ring together again?

Correct option is C

​Given:

There are four table clocks. They ring every 10 min , 15 min , 20 min and 25 min respectively

Solution:

LCM(10, 15, 20, 25)  = 300

Thus, the clocks will all ring together again after 300 minutes.

Since the clocks all ring together at 10 a.m., we add 5 hours to 10 a.m., which gives:

10 a.m. + 5 hours = 3 p.m.

Thus, The clocks will all ring together again at 3:00 p.m..