Given height off frustum cone = 16cm

Diameter of lower end of bucket (d_{1}) = 16cm

Lower and radius (r_{1}) = 16/2 = 8cm

Upper and radius (r_{2}) = 40/2 = 20cm

Let ‘l’ be slant height of frustum of cone

Slant height of frustum cone (l) = 20cm

Curved surface area of frustum cone