If the area of a circle decreases by 36%, then the radius of a circle decreases by Choose the correct option.
A) 20 % B) 18 % C) 36 % D) 64 % E) none of these

Rationale: "if area of a circle decreased by x % then the radius of a circle decreases by ( 100 − 10 √ 100 − x ) % = ( 100 − 10 √ 100 − 36 ) % = ( 100 − 10 √ 64 ) % = 100 - 80 = 20 % answer a"
Answer: A