Kaitlin's company makes solid metal balls for various industrial uses. a customer wants iron balls that have a diameter of 9in . if kaitlin must make 30 of these balls, how much iron will she need? use 3.14 for π , and do not round your answer.

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.