2015 · Q73
A water tank, open at the top, is hemispherical at the bottom and cylindrical above it. The radius is 12 m and the capacity is 3312π m³. The ratio of the surface areas of the spherical and cylindrical portions is
Elementary MathematicsMensuration
- A3:5
- B4:5
- C1:1
- D6:5
Explanation
(2/3)*pi*12^3 + pi*12^2*h = 3312*pi gives h = 15; the surface areas 2*pi*12^2 = 288*pi and 2*pi*12*15 = 360*pi are in ratio 4:5. Hence option (b).