# 4 Bells toll together at 9: 00 AM. They toll after 7, 8, 11, and 12 seconds respectively. How many times will they toll together again in the next 3 hours?

By BYJU'S Exam Prep

Updated on: September 25th, 2023

They will toll together 5 times again in the next 3 hours. We must determine the L.C.M of the given numbers in order to determine the time at which all bells will ring simultaneously.

therefore LCM of 7, 8, 11, and 12 = 1848

Bells will toll together after every 1848 seconds or 1848/60 = 30.80 ≈ 31 minutes

In three hours, no.of seconds = 30 x 3600 = 108000 seconds

In three times or three hours, bells will toll = 108000/1848 = 5 times

Following 9:00 AM, the bells will ring in the following order for the following three hours.

9:00 AM, 9:31 AM, 10:02 AM, 10:33 AM, 11:04 AM and 11:35 AM

### Formula of LCM

In mathematics, the value that is equally divided by the two supplied numbers is known as the LCM of any two. The Least Common Multiple is its full name. Another name for it is the Least Common Divisor (LCD).

When the fractions’ denominators differ, LCM can also be used to add or subtract any two fractions. LCM is used to make the denominators common when doing any arithmetic operations using fractions, such as addition and subtraction. The simplifying process is facilitated by this procedure.

Let a and b be two integers that are known. The following is the formula to determine the LCM of a and b:

LCM (a,b) = (a x b)/GCD(a,b)

GCD (a,b) refers to the greatest common factor or greatest common denominator of a and b.

Summary:

## 4 Bells toll together at 9: 00 AM. They toll after 7, 8, 11, and 12 seconds respectively. How many times will they toll together again in the next 3 hours?

4 Bells toll together at 9: 00 AM. They toll after 7, 8, 11, and 12 seconds respectively. They will toll together 5 times again in the next 3 hours. There are three important methods by which we can find the LCM of two or more numbers. They are listing the multiples, prime factorisation method, and division method.

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