Question

The radius of a hemispherical balloon increases from 6 cm to 12 cm as air is being pumped into it. The ratio of the surface areas of the balloon in the two cases is ___ *



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Answer 1

We know,

$\small \textbf{Surface Area of Hemisphere} = \tt \blue{3 \pi{r}^{2} }$

Now,

• Ratio of Surface Areas of balloons in two cases --

$= > \frac{ \tt { \cancel{3 \pi}{r}^{2} }}{ \tt { \cancel{3 \pi}{R}^{2} }} \\ \\ = > \frac{ {r}^{2} }{ {R}^{2} } = \frac{ {(6)}^{2} }{ {(12)}^{2} } \\ \\ = > \frac{36}{144} \: \: = \frac{1}{4} \\ \\ \huge = > \pink{1 : 4}$

Answer 2

Answer:

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