A toy is a cone mounted on a hemisphere, both of radius 3.5 cm. The total height of the toy is 15.5 cm. Find its total surface area in ${\text{cm}}^2$. Take π = 22/7.

Cone height = 15.5 − 3.5 = 12 cm, so its slant height = √$(12^2+3.5^2)=$ √156.25 = 12.5 cm. Curved surface of the cone = $(22/7)\times 3.5\times 12.5=137.5{\text{cm}}^2$; curved surface of the hemisphere = $2\times (22/7)\times 12.25=77{\text{cm}}^2$. The flat circle is hidden inside the join, so the total $=137.5+77=214.5{\text{cm}}^2$.