Combination Book Problem

Question

I need a help in Combination

Question:

In how many ways can $21$ identical Physics books and $19$ identical Chemistry Books to be arranged in row on a shelf, so that two chemistry books may not be together?

score 1 · Accepted Answer · 2015-09-19T07:27:55.637

1

First place all the $21$ Physics books in a row.

Then there are $22$ places to place the chemistry books, but we have to place only $19$ books.

So, the no. of way is $${22\choose 19}={22\choose 3}$$

edited Sep 19 '15 at 07:27

answered Sep 19 '15 at 07:22

@Balla, Did you got this, or I have to explain a bit more. – Sep 19 '15 at 07:29
i have got it and answer also correct Very Thank you – Math Boy Sep 19 '15 at 07:31

Combination Book Problem

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