## College Algebra (6th Edition)

The number of ways the first four finishers come in $6_{{P}{_{4}}}$ = 360
Total number of automobiles enter in the race = 6 Number of finishers = 4 To find the number of ways the first four finishers come in we use the formula $n_{{P}{_{r}}}$ = $\frac{n!}{(n - r)!}$ The number of ways the first four finishers come in $6_{{P}{_{4}}}$ = $\frac{6!}{(6 - 4)!}$ = $\frac{6!}{2!}$ = $\frac{6\times5\times4\times3\times2!}{2!}$ = $6\times5\times4\times3$ = 360