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Question
How many different selections of 4 books can be made from 10 different books, if
there is no restriction;
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Solution
Required ways of selecting 4 books from 10 books without any restriction =\[{}^{10} C_4 = \frac{10}{4} \times \frac{9}{3} \times \frac{8}{2} \times 7 = 210\]
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