Question

5. If the radius of a circle is increased by 20% then the area is increased by :

A. 44%
B. 120%
C. 144%
D. 40%
None of the above​

Answer 1

example :
radius of the circle ( before ) = 10cm
radius of circle ( after )
100% = 10
120% = 12

area of circle before = pi x 10 square = 314.15

area of circle after = pi x 12 square = 452.38

percentage increased
= area of circle ( after ) - area of circle ( before ) divides by area of circle (before) x 100%

= 44%

Answer : A

(Sorry if it’s wrong , I tried my best )

Answer 2

A. 44 %

Explanation:

Suppose Area of a circle is A=πr^2 (1)

When radius increase by 20%

r'=r + 20/100 r = 1.2 r

Now area

Area = πr'^2

= π (1.2 r)^2

= 1.44πr^2 (2)

Difference between the area (1) and (2)

=1.44πr^2-πr^2

= .44πr^2

Taking percentage

=.44πr^2*100/πr^2

=44%

Hence 44% is answer.