Question

1) A jury pool consists of 26 people, 18 men and 8 women. Compute the probability that a randomly selected jury of 12 people is all male.

2)You own 11 CDs. You want to randomly arrange 8 of them in a CD rack. What is the probability that the rack ends up in alphabetical order? Be sure to leave your answer as a fraction in order to earn credit.

Answer 1

1) Number of ways to select r items from n, nCr = n!/(r! x (n-r)!)

P(a randomly selected jury of 12 people is all male) = Number of ways to select 12 people from 18 males / Number of ways to select 12 people from total 26

= 18C12 / 26C12

= 21/10,925

= 0.00192

2) Permutation, nPr = n!/(n-r)!

Number of ways in which 8 CDs can be arranged from 11, 11P8

= 11!/3!

= 6,652,800

P(the rack ends up in alphabetical order) = 1/Number of ways in which 8 CDs can be arranged from 11

= 1/6,652,800