There is a young boy's birthday party which 3 friends have attended. The mother has arranged 10 games where a prizeis awarded for winning a game. The prizes are identical. If each of the 4 children receives at least one prize, then howmany distributions of prizes are possible?
Explanation
Concept:
- The total number of ways in which n objects can be distributed in r people if any person can get 'any number of objects' = nr−1Cr−1.
- The total number of ways in which n objects can be distributed in r people if every person must get 'at least one object' = n−1Cr−1.
- nCr=r!(n−r)!n!.
- n!=1×2×3×...×n.
- 0!=1.
Calculations:
Here, the number of objects is n = 10 and the number of people is r = 4.
Since, every person must get at least one object, the total number of possible distributions is:
n−1Cr−1=10−1C4−1=9C3=3!(9−3)!9!=3×2×17×8×9=84.