Two numbers are in the ratio $5:6$. If their $H.C.F.$ is $4$,then their $L.C.M.$ will be

In a school,$391$ boys and $323$ girls have been divided into the largest possible equal classes,so that each class of boys numbers the same as each class of girls. What is the number of classes?

The traffic lights at three different road crossings change after every $48\, seconds,$ $72\, seconds$ and $108\, seconds,$ respectively. If they all change simultaneously at $8: 20: 00$ $hours,$ then they will again change simultaneously at

Three electronic devices make a beep after every $48\, seconds$,$72\, seconds$,and $108\, seconds$ respectively. They beeped together at $10:00\, a.m.$ The time when they will next make a beep together at the earliest is:

The sum of two numbers is $216$ and their $H.C.F.$ is $27$. The numbers are

There are five bells which start ringing together at intervals of $3, 6, 9, 12$ and $15$ seconds respectively. In $36$ minutes,how many times will the bells ring simultaneously?