Question

Total surface area of a solid hemisphere is 4158cm², the diameter of the hemisphere is equal to __________ cm.
(Take $\pi$ = $\frac{22}{7}$)

• A. 20
• B. 21
• C. 40
• D. 42

Answer 1

The correct option is D 42

We know that total surface area of a hemisphere =$3\pi r^2$

$3\pi r^2$= 4158
$3\times \frac{22}{7}\times r^2=4158$
$r^2=\frac{4158\times 7}{3\times 22}=\frac{29106}{66}=441$
$r^2=441$
Hence, r = 21 cm.
Therefore, diameter of solid hemisphere = 2r = 2 $\times$ 21 = 42cm.