A and B are two circles. The radius of A is four times as large as the diameter of B. What is the ratio between the areas of the circles?  Pick one.
A) 1 : 8 .
B) 1 : 2 .
C) 1 : 24 .
D) 1 : 64 .
E) 1 : 6 .

Rationale: given : the radius of a is 4 times as large as the diameter of b . = > r ( a ) = 4 * d ( b ) = 4 * 2 * r ( b ) = 8 r ( b ) . the radius are in ratio of 1 : 8 thus the area will be in the ratio of square of radius . 1 : 64 . hence d .
Answer: D