$7.$ Interpreting Merge Steps from a Dendrogram. From $1946$ to $1990,$ the Big Ten Conference consisted of the University of Illinois, Indiana University, University of Iowa, University of Michigan, Michigan State University, University of Minnesota, Northwestern University, Ohio State University, Purdue University, and University of Wisconsin. In $1990,$ the conference added Pennsylvania State University. In $2011,$ the conference added the University of Nebraska. In $2014,$ the University of Maryland and Rutgers University were added to the conference with speculation of more schools being added in the future. Based on the football stadium capacity, latitude, longitude, and enrollment, the Big Ten commissioner is curious how a clustering algorithm would suggest the conference expand beyond its current $14$ members. To represent the $14$ member schools as an entity, each variable value for the $14$ schools of the Big Ten Conference has been replaced with the respective variable median over these $10$ schools. Using Euclidean distance to measure dissimilarity between observations, hierarchical clustering with complete linkage generates the following dendrogram. Describe the next three stages of conference expansion plan suggested by the dendrogram.