i need some help in stats pleasee?

A case of 24 cans contains 1 can that is contaminated. Three cans are to be chosen randomly for testing.

(a) How many different combinations of 3 cans could be selected?

Number of different combinations _____i got this to be 2024
(b)

What is the probability that the contaminated can is selected for testing?

Probability____ i cant get this one

peabody2010-02-07T17:37:51Z

Favorite Answer

a) 24C3 = 24!/21!3! = 24*23*22/6 =2024

b) Pr ( 2 perfect , 1 contaminated )

= 23C2 * 1C1 / 24C3

= 23*22/2 * 1 / 2024

= 251 /2024