Official Solution:What will be the percentage increase in the area of a circle if the circumference of the circle increases by 10%? (The area of a circle is calculated using the formula: \(area = \pi r^2\), where \(r\) is the radius. The circumference of a circle is calculated with the formula: \(circumference = 2\pi r\).) A. 20%
B. 21%
C. 36%
D. 40%
E. 44%
The circumference of the circle increases by 10%" implies that the radius of the circle also increases by 10%. The new area becomes \(\pi(1.1r)^2 = 1.21\pi r^2\). Hence, the area increases by 21%.
Answer: B