Question

Adric owns 8 pairs of shoes. How many ways can he choose 4 pairs of shoes to pack into his luggage?

The answer is 70 but I don’t know how my teacher got that...

Answer 1

70

Explanation:

It is made with a combination. Combination of 4 taken from 8, the formula of the combination is as follows:

nCr = n! / (r! * (n-r)!)

In this case 8 is "n" and 4 is "r"

8C4 = 8! / (4! * (8-4))!

8C4 = 8! / (4! * 4!)

8C4 = 40320/576

8C4 = 70

In this way he obtained the answer that is 70