The number of ways in which 2n distinct letters (addressed) can be distributed in N distinct mail boxes such that there are exactly K letters n

Question

The number of ways in which 2n distinct letters (addressed) can be distributed in N distinct mail boxes such that there are exactly K letters n<K≤2n in one of the mail boxes is

MARKS Content Team · Accepted Answer

Correct answer: (B) CK2n·NN-1^(2n-K). Select K letters from 2n in C_2nK ways. Select 1 of the mail boxes in C_N1 way. Remaining 2n-K letters each have N-1 options and can be allotted in N-1^(2n-K) ways. Hence, the required number of ways =CK2nC1NN-1^(2n-K).

The number of ways in which $2 n$ distinct letters (addressed) can be distributed in $N$ distinct mail boxes such that there are exactly $K$ letters $(n < K \leq 2 n)$ in one of the mail boxes is

Solution

More Permutation Combination Questions