Saved Bookmarks
| 1. |
Find the number of selections of one or more things from the group of p identical things of one type, q identical things of another type, r identical things of the third type and n different things. |
|
Answer» Solution :SINCE NUMBER of ways of selecting r things out of n identical things =1 for al `r LE n`. Number of ways of selecting zero or more things out of p identical things = p+1 Similarly, number of ways of selecting zero or more things out of q and r identical things is q+1 and r+1 RESPECTIVELY. Also, number of ways of selecting zero or more things out of n different things `=2xx2xx2xx..` n times `=2^(n)` Therefore, total number of ways of selecting zero or more things out of all given things `=(p+1)(q+1)(r+1)2^(n)` But number of ways of selecting one or more things out of given things `=(p+1)(q+1)(r+1)2^(n)-1`. |
|