Question

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

Answer 1

D on edge

Explanation:

Answer 2

76.5

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((n-1)!)/(2)=((2-1)!)/(2)+((3-1)!)/(2)+((4-1)!)/(2)+((5-1)!)/(2)+((6-1)!)/(2)=\\\\=(1!)/(2)+(2!)/(2)+(3!)/(2)+(4!)/(2)+(5!)/(2)=(1)/(2)+(1*2)/(2)+(1*2*3)/(2)+(1*2*3*4)/(2)+(1*2*3*4*5)/(2)=\\\\=(1)/(2)+1+3+12+60=\boxed{76.5}`