9 has the greatest value because it’s positive
Sector area = (central angle / 360) * PI * radius^2
sector area = (72 / 360) * PI * radius^2
radius^2 = sector area / [(72 / 360) * PI]
radius^2 = 16.2 * PI / [(1 / 5) * PI]
radius^2 = 16.2 / .2
radius^2 = 81
radius = 9
Source:
http://www.1728.org/radians.htm
18 girls
Half of the students volunteer
15 don't -- so the other half must be 15 as well making there 30 students in the class.
If 12 are boys, then 30(students in class) - 12 (boys) = 18 girls
