Question

Three bells ring at intervals of 12,15 and 18 seconds respectively.If they start ringing together at 8:35am at what time will they ring together again at the earliest?????

Answer 1

$lcm \: of \: 12 \: 15 \: 18 \: is \: 180 \\ on \: changing \: lcm \: into \: hours = \frac{180}{60} = 3 \: hours \\ the \: bell \: will \: ring \: again \: at \: earliest \: = 8: 35 + 3: 00 \\ at \: 11: 35 \: am \: the \: bells \: will \: ring \: again$

Answer 2

Answer:

8:38 a.m.

Step-by-step explanation:

Given :

Three bells ring at intervals of 12, 15 and 18 seconds respectively.

Taking the LCM of 12, 15 and 18 :-

12 =  2 * 2 *3

15 =  3 * 5

18 =   2 * 3 * 3

LCM = 2 * 2 * 3 * 3 * 5 * 2 * 3 * 3 = 180

180 is common in 12, 15 and 18. Therefore, LCM of 12, 15 and 18 is 180.

Given : They started ringing together at 8:35 a.m.

Second time they ringing together = 8:35 + 180 seconds = 8:35 + 3 minutes = 8.38 a.m.

Hence,

Second time they ringing together at 8:38 a.m.