Chapter 12 - Data Analysis and Probability - 12-6 Permutations and Combinations - Practice and Problem-Solving Exercises - Page 766: 25

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This question involves permutations. The number of books read is: $_{10}P_4$ We know that: $_nP_r = \frac{n!}{(n-r)!}$ $_{10}P_4= \frac{10!}{(10-4)!}$ $\frac{10!}{6!}$ We also know that: $x! = x(x-1)(x-2)...(1)$ Thus, we have: 5040