If the diameters of a circle is increased by 100% . Its area is increased by?

• A. 400%
• B. 200%
• C. 300%
• D. 100%

Answer: (C)

Original area = ?(d/2)2= (?d2) / 4New area = ?(2d/2)2= ?d2Increase in area = (?d2 - ?d2/4)= 3?d2/4? Required increase percent = [(3?d2)/4 x 4/(?d2) x 100]%= 300%