Answer:
76.5
Step-by-step explanation:
Recall that for any positive integer n
n! = 1*2*3*4*...*n
For example
5! = 1*2*3*4*5 = 120
so
[tex]\sum_{n=2}^6\frac{(n-1)!}{2}=\frac{(2-1)!}{2}+\frac{(3-1)!}{2}+\frac{(4-1)!}{2}+\frac{(5-1)!}{2}+\frac{(6-1)!}{2}=\\\\=\frac{1!}{2}+\frac{2!}{2}+\frac{3!}{2}+\frac{4!}{2}+\frac{5!}{2}=\frac{1}{2}+\frac{1*2}{2}+\frac{1*2*3}{2}+\frac{1*2*3*4}{2}+\frac{1*2*3*4*5}{2}=\\\\=\frac{1}{2}+1+3+12+60=\boxed{76.5}[/tex]
D on edge
