In how many ways can 3 singers be selected from 5 who came to an audition?
There are 10 ways in which 3 singers can be selected from 5 who came to an audition. This can be calculated using the combination formula:
C(n, r) = n! / (r!(n-r)!)
where n is the total number of singers (5) and r is the number of singers to be selected (3).
C(5, 3) = 5! / (3!(5-3)!) = 5! / (3!2!) = (5x4x3) / (3x2) = 10
Therefore, there are 10 ways in which 3 singers can be selected from 5 who came to an audition.