Question

Jeanine is selecting various albums to be displayed in the front of her music coffee house. She will be choosing 4 albums for

one part of the display. This part of the display is very prominent and she is really trying to promote jazz. There are five albums
from Diana Kroll, seven albums from Harry Connick Jr. and four albums from Michael Bublé. In how many ways can she choose
four albums for display and at least two albums are from Diana Kroll? Evaluate using both the direct and indirect method.
Gt11.2014

Answer 1

The number of ways she can choose four albums for display with at least two from Diana Kroll is from the sixteen albums is 665 ways

Explanation:

1) The number of ways she can choose 2 albums of Diana from the 5 Diana Kroll albums is 5!/(2!(5 - 2)!) = 10 ways

Choosing the other 2 albums from the remaining 11 albums gives;

11!/(2!(11 - 2)!) = 55 ways

Total number of ways is then 10 × 55 = 550 ways

Choosing 3 from the 5 Diana Kroll albums is 5!/(3!(5 - 3)!) = 10 ways

Choosing the other 1 album from the remaining 11 albums gives;

11!/(1!(11 - 1)!) = 11 ways

Total number of ways is then 10 × 11 = 110 ways

Choosing 4 from the 5 Diana Kroll albums is 5!/(4!(5 - 4)!) = 5 ways

Choosing the other 0 album from the remaining 11 albums gives;

11!/(0!(11 - 0)!) = 1 way

Total number of ways is then 5 × 1 = 5 ways

Total number of ways = 550 + 110 + 5 = 665 ways

2) In the indirect method, we first find the number of ways to choose 4 albums out of the 16 albums, then we subtract the number of cases where there are 1 and 0 Diana Kroll albums as follows;

16!/(4!(16 - 4)!) = 1820 ways

With 1 Diana Kroll album gives

5!/(1!(5 - 1)!)×11!(3!(11 - 3)!) = 825 ways

With 0 Diana Kroll album gives

5!/(0!(5 - 0)!)×11!(4!(11 - 4)!) = 330 ways

Total number of ways with at least 2 Diana Kroll albums = 1820 - 825 - 330

Total number of ways with at least 2 Diana Kroll albums = 665 ways.