A histogram is being made for the following list of data. If the length of each interval is going to be 5, what will be the
frequency of the second Interval?
78, 92, 98, 87, 86, 72, 92, 81, 86, 92

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.