Question

Nandini has to place 5 different books in 4 different shelves. In how many ways can she place these books such that each shelf has at least one book?/

Answer 1

Answer:

she will keep the bopks in 20 ways

Answer 2

15504 is the number of ways

Step-by-step explanation:

This is a question of combinations.

Here, no. of books is 20 and number of shelves is 5, so that gives the number of combinations to us as $^{n}C_{r}\textrm{}$

Using the formula that $^{n}C_{r}\textrm{}= \frac {n!}{(n-r)!.r!}$,

$\frac {20!}{(20-15)!.5!}$ is the number of combinations

This would eventually come out to be 15504