2017 · Q85
If the surface area of a sphere is reduced to one-ninth of the area, its radius reduces to
Elementary MathematicsMensuration
- AOne-fourth
- BOne-third
- COne-fifth
- DOne-ninth
Explanation
This tests quadratic scaling of surface area. Surface area ∝ r², so reducing the area to 1/9 scales the radius by √(1/9) = 1/3. Option (d) "one-ninth" is the trap from applying the area factor directly to the radius. Hence option (b).