If a large pizza has a radius that is 10% larger that that of a medium pizza, what is the percent increase in area between a medium and a large pizza?
Answers: A) 15 % B) 21 % C) 25 % D) 30 % E) 36 %

Rationale: "let the radius of medium pizza be r . then the radius of large pizza is 1.1 r . the area of the medium pizza is pi * r ^ 2 the area of the large pizza is pi * ( 1.1 * r ) ^ 2 = 1.21 * pi * r ^ 2 , an increase of 21 % . the answer is b ."
Answer: B