A toy is in the form of a cone mounted on a hemisphere of common base radius 7 cm.

Radius of the hemisphere = Radius of the cone = 7 cm

Height of the cone $=(31-7) \mathrm{cm}=24 \mathrm{~cm}$

Slant height of the cone, $l=\sqrt{r^{2}+h^{2}}$

$=\sqrt{(7)^{2}+(24)^{2}}$

$=\sqrt{49+576}$

$=\sqrt{625}$

$=25 \mathrm{~cm}$

Total surface area of the toy = (Curved surface area of the hemisphere) + (Curved surface area of the cone)

$=2 \pi r^{2}+\pi r l$

$=\pi \times r \times(2 r+l)$

$=\frac{22}{7} \times 7 \times(14+25) \mathrm{cm}^{2}$

$=858 \mathrm{~cm}^{2}$