Question

A watch manufacturing company is testing watch alarms. They program alarms of all the watches to
beep simultaneously. The alarms start beeping at intervals of 5, 8, 10, 15 and 21 seconds respectively.
In an hour, how many times do the alarms beep together?​

Answer 1

Step-by-step explanation:

at second second it will interval of by watch

Answer 2

Given:

The intervals=5, 8, 10, 15 and 21 seconds

To find:

The number of times the alarms beep together in an hour

Solution:

The number of times the alarms beep together in an hour is 4.

We can find the number by following the given process-

We know that the LCM of intervals of all the alarms needs to be calculated to obtain the number of times all the alarms will beep together.

The intervals of all alarms: 5, 8, 10, 15, 21

We will calculate the LCM of 5, 8, 10, 15, 21=840

So, all the alarms will beep together after every 840 seconds.

We need to obtain the number of times they will beep together in an hour.

The number of seconds in an hour=3,600

The number of times all the alarms will beep together=Total seconds in an hour/ Seconds after which they beep together

=3,600/840

=4.28

Since it is not completely divisible, the alarms will beep together 4 times in an hour and again after the hour is finished.

Therefore, the number of times the alarms beep together in an hour is 4.