If the radius of a sphere is increased by 50%, find the percent increase in surface area.

125%

The correct answer is Option (1) → 125%

Surface area of a sphere ∝ $r^2$

Given:

Radius is increased by 50%

$\text{New radius} = 1.5r$

New surface area:

$(1.5r)^2 = 2.25r^2$

Increase in surface area:

$2.25r^2 - r^2 = 1.25r^2$

$\text{Percentage increase} = 1.25 \times 100 = 125\%$