If the area of a circle decreases by 42%, then the radius of a circle decreases by  Select.
A) 20 %	B) 18 %	C) 24 %	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 − 42 ) % = ( 100 − 10 √ 58 ) % = 100 - 76 = 24 % answer c"
Answer: C