The mean weight of the packages joan shipped was 2.5 pounds. if joan mailed four packages and three of them had weights of 1.7, 3.2, and 2.8 pounds, then what did the other package weigh?

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.