Answer
20
Work Step by Step
The number of possible combinations if r items are taken from n items is
nCr =$\frac{n!}{r!(n-r)!}$
The number of ways that 3 jokes can be ranked is
= 6C3 x 1!
=$\frac{6!}{(6-3)!3!}$
=$\frac{6*5*4*3!}{3!3!}$
=$\frac{6*5*4}{3*2*1}$
= 20 ways