Chapter 10 Counting Methods and Probability - 10.3 Define and Use Probability - 10.3 Exercises - Skill Practice - Page 702: 18

$\frac{1}{5040}$

We know that if we want to select $r$ objects out of $n$ regarding the order, we can do this in $_nP_r=\frac{n!}{(n-r)!}$ ways. Here we have $n=10$ and $r=4$; hence we have $_{10}P_4=5040$ total possible selections: $\frac{1}{5040}$