Question

Aldo has 8 CDs that he is going to give away. He lets his best friend choose 2 of the 8 CDs. How many different groups of 2 CDs are possible?

Answer 1

Answer:

28

Step-by-step explanation:

This problem can easily be solved by n c r formula :-

$\frac{(n!)}{r!*(n - r)!}$

The image given below will give you more clarity on n c r formula.

n = 8

r = 2

=> $\frac{8!}{2!*(8 - 2)!}$

=> $\frac{8!}{2!*6!}$

=> $\frac{8*7*6*5*4*3*2*1}{2*1*6*5*4*3*2*1}$

=> $\frac{8*7}{2*1}$

=> $\frac{56}{2}$ => 28