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CBSE Class 11-science Answered

A library membership allows 4 books to be borrowed at any given time. Rahul goes to the library and finds that he likes two books on a given shelf which contains 15 books in all. Rahul has decided that he would either take both the books or take none of these two. In how many ways can he select 4 books?

Asked by Topperlearning User | 13 Sep, 2016, 02:37: AM

Expert Answer

Rahul can either select both the books and select 2 out of the other 13 this can be done in ¹³C₂ ways.

Rahul can select 4 books leaving these 2 out which can be done in ¹³C₄ ways.

Hence total no of selections= $C presuperscript 13 subscript 2 plus C presuperscript 13 subscript 4$

Answered by | 13 Sep, 2016, 04:37: AM

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