Question 2031
After folded the top of the cone is a  circle which perimeter is equal to
 the length of the arc of the sector. It is 16 pi/2 = 8pi cm.

 Hence,the radius of the top circle is 8pi/2pi= 4 cm.

   ------- (the diameter of the top is 8cm)
   \  |
    \ | h (height of the cone)
     \|

  Note: the hypotenuse 16^2 = 4^2 + h^2, so h = 4^2(4^2 -1) = 15*4^2,
   so, h = 4  sqrt(15)

 Hence, the volume of the cone(1/3 area of Base * Height)
 = 1/3 pi r^2 h = 1/3 pi 4^2 *4 sqrt(15)
  = 64 sqrt(15)/3 cm^3

 Kenny