JAMB 1989 · UME · Q9

Solid mensuration

If the surface area of a sphere is increased by $44\%$ , find the percentage increase in its diameter.

Worked solution (try it first)

Surface area goes with the square of the diameter.
A 44% increase multiplies the area by 1.44.
So the diameter is multiplied by $\sqrt{1.44} = 1.2$ .
That is a 20% increase, option D.

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