Correct Answer - Option 3 : 3:00pm
Given:
Three electronic devices make a beep after 15 minutes, 20 minutes and 30 minutes respectively.
All beeped together at 2:00 pm noon.
Concept used:
In this type of question, you should take lcm of given data for next time meeting, beeping or anything.
Calculation:
LCM of 15, 20 and 30
15 = 3 × 5
20 = 22 × 5
30 = 2 × 3 × 5
LCM = 22 × 3 × 5 = 60
Next time they will together beep after 60 minutes.
(∵ 60 minutes = 1 hours)
∴ Next time they will together beep at 3:00 pm.