Question

A class prefect goes to meet the principal every week. His class has 30 people apart from him. He has to take groups of three every time he goes to the principal, in how many weeks will he be able to go to the principal without repeating the group of same three which accomplice him?

Answer 1

I think the answer is 10 weeks
As he has to take group of 3 along him
And there are 30 students apart him
So he can make 10 groups (30/3)


I hope this will help

Answer 2

It's not that simple.

There are 30 students to be taken in groups of 3. As the sequence in the group doesn't matter, we will use combination.

So, number of possible groups

= 30 C 3

= 30! / 3! . 27!

= 30 . 29 . 28 / 6

= 5 . 812

= 4060

As 1 group goes per week, 4060 is the number of weeks in which the prefect will be able to go to the principal without repetition of same group