1.A frustum is formed by cutting off the upper part of a solid wooden right circular cone. The radii of the circular top and the circular base of the frustum is 4cm and 6cm respectively, and the slant height of the frustum is 7cm.
Given that a cylindrical hole of radius of 2cm is drilled through the centre of the frustum and the cylinder is removed. The hollow frustum is now as shown in the diagram below.
(a) Calculate the height of the hollow frustum.
(b)If the cylindrical wood which was removed from the centre of the frustum had a total mass of 55g, calculate the density of the wood in g / c * m ^ 3
(c) Show that the slant height of the cone that was cut off is 14cm.
(d) Calculate the total surface area of the hollow frustum.
(e) Calculate the volume of the hollow frustum.
Volume of a cone of radius r and vertical height h is 1/3 * pi * r ^ 2 * h
Curved surface area of cone of radius r and slant height I is pi*rl
