Ace Test Series: Discrete Maths - Combinatory

Question

Comments

9  ?

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No answer given as 540 ... They are using onto fuction but i m not getting why so

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I did like this.
It can be 1 1 4 type or 1 2 3 type distribution.
1 1 4 can be arranged in 3 ways and 1 2 3 in 6 ways. So 9 ways.
Since they are different books, we can arrange them in 6! ways.
But 6! * 9 = 6480 :p

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Nope... Answer is 540

Answer 1

540 will be answer

Comments

I didn't get the method

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hmm its distribution and division of object , i studied from many places :P

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I also didn't understood this method do you have any source to study this method?

Its like permutation with repetition method right??