Question

the radius of a spherical balloon increases from 7 cm to 14 cm. find the ratio of surface area of the balloon in both cases

Answer 1

Heyaa...☺☺✌

Total surface area of sphere =
$4\pi {r}^{2}$

Surface area of 1st balloon =
$= > 4\pi {r}^{2} \\ \\ = > 4 \times \frac{22}{7} \times 7 \times 7 \\ \\ = > 4 \times 22 \times 7 \\ \\ = > 616 {cm}^{2}$
Surface area of 2nd balloon =

$= > 4\pi {r}^{2} \\ \\ = > 4 \times \frac{22}{7} \times 14 \times 14 \\ \\ = > 4 \times 22 \times 2 \times 14 \\ \\ = > 2464 {cm}^{2}$

So the ratio of balloons in both the cases

=> 616 /2464
=> 616 : 2464
=> 1 : 4

Thanks...☺☺✌

Answer 2

In this question we will find Surface area.

Surface Area of Sphere when radius is 7 cm.

=> S.A = 4πr^2

=> S.A = (4 x 22/7 x 7 x 7) cm^2

=> S.A = 616 cm^2

Again,

Surface area of Sphere when radius is 14 cm.

=> S.A = 4πr^2

=> S.A =( 4 x 22/7 x 14 x 14) cm^2

=> S.A = 2464 cm^2


=> Ratio = 616/2464 = 1/4 = 1:4




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