Respuesta :
Answer:
The number of ways they can finish in first, second, and third place is:
6840
Step-by-step explanation:
We know that choosing and arrangement of r items out of a total of n items is done by the method of permutation.
The formula is given by:
[tex]n_P_r=\dfrac{n!}{(n-r)!}[/tex]
Here we have to chose 3 entries and arrange them according to there ranks.
Hence, we have n=20 and r=3
Hence, the formula is given by:
[tex]{20}_P_3=\dfrac{20!}{(20-3)!}\\\\\\{20}_P_3=\dfrac{20!}{17!}\\\\\\{20}_P_3=20\times 19\times 18\\\\\\{20}_P_3=6840[/tex]
