2. The ratio of surface area of a sphere and curvedarea of a hemispher

1.	2. The ratio of surface area of a sphere and curvedarea of a hemisphere is 9:2. Find ratio of their volumes.
Answer» Let radius of sphere be r1Let radius of hemisphere be r2 Surface area of Sphere A1 = 4pir1^2 Curved surface area of Hemisphere A2 = 2pir2^2 As per given conditionA1/A2 = 9/22r1^2/ = 9/2r2^2 r1/r2 = 3/2 Ratio of volume of sphere V1 to volume of hemisphere V2 V1/V2 = 4/3pir1^3/2/3pir2^3 = 2(r1/r2)^3 = 2(27/8) = 27/4 wrong answer

2. The ratio of surface area of a sphere and curvedarea of a hemisphere is 9:2. Find ratio of their volumes.

Answer»

Let radius of sphere be r1Let radius of hemisphere be r2

Surface area of Sphere A1 = 4*pi*r1^2

Curved surface area of Hemisphere A2 = 2*pi*r2^2

As per given conditionA1/A2 = 9/22*r1^2/ = 9/2r2^2

r1/r2 = 3/2

Ratio of volume of sphere V1 to volume of hemisphere V2

V1/V2 = 4/3*pi*r1^3/2/3*pi*r2^3 = 2*(r1/r2)^3 = 2(27/8) = 27/4

wrong answer