How often will five bells toll together in one hour if they start together and toll at intervals of $5, 6, 8, 12, 20$ seconds,respectively?

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?

Three different containers contain different quantities of a mixture of milk and water,measuring $403 \ kg$,$434 \ kg$,and $465 \ kg$. What is the largest measure that can measure all these quantities exactly? (in $kg$)

The greatest number,which when subtracted from $5834$,gives a number exactly divisible by each of $20, 28, 32$ and $35$,is

The maximum number of students among whom $1001$ pens and $910$ pencils can be distributed in such a way that each student gets the same number of pens and the same number of pencils is:

Find the greatest number which will divide $3962, 4085$ and $4167$ leaving the same remainder in each case.