Question

The diameter of a spherical balloon increases from 14cm to 28 cm as air is being pumped into it find the ratio of surface aera of the baloons in two cases

Answer 1

Surface area of balloon = 4*π*r^{2};

CASE I :

diameter = 14 cm ⇒ radius = 7 cm
 Surface area of balloon (S1) = 4*π*7^{2} cm^{2}

CASE II :

diameter = 28 cm ⇒ radius = 14 cm
 Surface area of balloon (S2) = 4*π*14^{2} cm^{2}

Ratio of surface areas in two cases  = S1/S2 = 4*π*7^{2} / 4*π*14^{2} = 7*7 /14*14 = 1 / 4
Thus ratio of surface areas S1 : S2 = 1 : 4

Answer 2

1:4 is ur answer. hope it works