Hardcover Paperback Total
Detective Novels 12 20 32
Romance Novels 8 28 36
Other 9 14 23
Total 29 62 91
1. Detective Novel = 32 / 91 = .35
2. Hardcove Book = 29 / 91 = .32
3. Paperback Detective Novel = 20/91 = .22
4. Paperback or Detective Novel = [ 62 + 32 - 20] / 91 = 74/91 = .81
5. Not a Detective novel = [ 36 + 23 ] / 91 = 59/91 = .65