Question

Can someone explain to me how to do this? Im completely confused. Please and thanks

Answer 1

45

Explanation:

Each handshake is between 2 people, so you need to find how many combinations of 2 can be formed from a group of 10 people.

n = 10 and k = 2:

₁₀C₂

10! / (2! (10−2)!)

10! / (2! 8!)

10 × 9 × 8! / (2! 8!)

10 × 9 / 2

45