Question

20) If the radius of a circle is increased by 30%, then the area is increased by:
A) 120%
B) 69%
C) 160%
D) 169%
E) None of the above​

Answer 1

Answer:

B) 69%

Step-by-step explanation:

let  radius be r

after increasing 30% radius becomes R = 1.3r

New area= π R²

New area = π (1.3r)²= 1.69π r²

Previous area= π r²

change in area=1.69π r² - π r² = 0.69 π r²

% increased =  (0.69π r²/ π r²) ×100%  =69%