Question

an electronic device makes a beep together after every 15 minutes another device makes a beep after every 20 minutes they b together at 6 A.M at what time will they next beep together

Answer 1

sorry 7:00 am.hope it helps u

Answer 2

The electronic device will beep together at 7 am

Solution:

The electronic device makes a beep together after every 15 minutes another device makes a beep after every 20 minutes

LCM is the minimum number that is divisible by both the numbers,

So, the minimum common time after they will beep is the LCM of 15 and 20

Factors of 15 = $1\times5\times3$

Factors of 20 = $1\times5\times2\times2$

LCM of 15 and 20 is 60

So they will beep after 60 min =1 hour, hence it will again ring at 7 am.