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 balloons in two cases is(a) 1:4 (b) 1:3 (c) 2:3 (d) 1:2

The radius of a hemispherical balloon increases from 6 cm to 12 cm as

1.	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 balloons in two cases is(a) 1:4 (b) 1:3 (c) 2:3 (d) 1:2
Answer» The radius of a hemispherical balloon increases from $6 c m$ to $12 c m$ as air is being pumped into it. The ratio of the surface areas of the balloons in two cases is (a) $1 : 4$ (b) $1 : 3$ (c) $2 : 3$ (d) $1 : 2$