Answer
The number of ways the first four finishers come in $6_{{P}{_{4}}}$ = 360
Work Step by Step
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
