Question

There are three copies of 4 different books . In how many ways can they be arranged on a shell ?​

Answer 1

Answer:

Let each different book be indicated as A, B, C and D.

Each book has 3 copies so one such arrangement is given below.

AAABBBCCCDDD

Here we got 12 letter word with 4 letter recurring 3 times.

Now I am changing the question as the following :

'How many meaningful and non - meaningful words can be formed by rearranging the letters in the word'

AAABBBCCCDDD

Here the answer is,

=> 12!/3!*3!*3!*3!

=>12*11*10*9*8*7*6*5*4*3*2*1/6*6*6*6

=> 12*11*10*8*7*5

=> 369,600

Thus we can arrange 3 copies of 4 different books on a shelf in 369,600 ways.

Answer 2

Answer:

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