Two simple pendulums of time periods 2.0s & 2.1s are made to vibrate simultaneously. They are in phase initially , after how may vibrations are there in the same phase ?

Two simple pendulums of time periods 2.0s & 2.1s are made to vibrate s

1.	Two simple pendulums of time periods 2.0s & 2.1s are made to vibrate simultaneously. They are in phase initially , after how may vibrations are there in the same phase ?
Answer» 21 25 30 35 Answer :A