Question

12. The radius of a hemispherical balloon increases from 6 cm to 12 cm as air is being pumped into
it. The ratios of the surface areas of the balloon in the two cases is
(1 Point)
O (A) 1:4
(B) 1:3
O (0) 2:3
(D) 2:1​

Answer 1

Answer:

Total surface area of a Hemisphere =2πr

2

+πr

2

=3πr

2

r=6,Surface area=3π(6)

2

=36

r=12,Surface area=3π(12)

2

=144

Ratio = 36:144

=1:4