Question

What is the value of ?A. 7.5 B. 17.5 C. 60.5 D. 76.5

Answer 1

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

$\sum_{n=2}^6\frac{(n-1)!}{2}=\frac{(2-1)!}{2}+\frac{(3-1)!}{2}+\frac{(4-1)!}{2}+\frac{(5-1)!}{2}+\frac{(6-1)!}{2}=\\\\=\frac{1!}{2}+\frac{2!}{2}+\frac{3!}{2}+\frac{4!}{2}+\frac{5!}{2}=\frac{1}{2}+\frac{1*2}{2}+\frac{1*2*3}{2}+\frac{1*2*3*4}{2}+\frac{1*2*3*4*5}{2}=\\\\=\frac{1}{2}+1+3+12+60=\boxed{76.5}$

Answer 2

Answer:

D on edge

Step-by-step explanation: