The total surface area of a hemisphere is $4158{ \mathrm{cm}}^2$. Find the diameter of the hemisphere. $\left(\text{Take }\pi =\frac{22}{7}\right)$

Concept: We know the total surface area of a hemisphere is $3\pi r^2$.

Here, $3\pi r^2=4158$

$\Rightarrow 3\times \frac{22}{7}\times r^2=4158$

$\Rightarrow r^2=441$

$\Rightarrow r=21 \text{cm}$

Therefore, diameter of hemisphere $=2r=42 \text{cm}$.

Hence, the diameter of the hemisphere is $42 \text{cm}$.