2022-06-30

In how many ways can 5 letters be mailed if there are 2 mailboxes available?

Monserrat Cole

Expert

Explanation:
We can mail N letters in one box, and the remaining $5-N$ in the other, for $N=0,1,2,3,4,5.$.
We can select N out of 5 in $5{C}_{N}$ ways.
So, the total number of all possible ways is $\sum 5{C}_{N}$, $N=0,1,2,3,4,5.$.
This sum is $1+5+10+10+5+1=32.$

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