A person has three different bags and four different books. The number of ways, in which he can put these books in the bags so that no bag is empty, is :
Solutions · 1
Official solution
We distribute 4 distinct books into 3 distinct bags with none empty. The only possible distribution pattern is (2,1,1).
Choose which 2 books go together: (24)=6. Arrange the resulting 3 groups into the 3 distinct bags: 3!=6.
\[\text{Total} = 6 \times 6 = 36\]