Question

In a call centre at New Delhi,it is observed that it gets a call at an interval of every 10 minutes from California,at an interval of every 12 minutes from Texas,at an interval of 20 minutes from Washington DC and after every 25 minutes it gets a call from London.If in the early morning at 5 : 00 a.m. it has received the calls simultaneously from all the four destinations, then at what time again it will receive the calls at a time from all the places on the same day?

• A. $10:00$ a.m
• B. $3:00$ a.m
• C. $5:00$ p.m
• D. Both A and B

Answer 1

The correct option is A $10:00$ a.m

$LCM(10,12,20,25)=300$

So, at every $300mins$, the call centre will recieve calls from all of the above places simultaneously.

$300mins=\frac{300}{60}hrs=5hrs$.

So, the time at which the call centre will recieve simulteneous calls from all places $=5:00+5:00=10:00am.\left[A\right]$