The scatter plot shows the relationship between the number of hours spent practicing piano per week and the number of pieces of music the student can play:

a scatter plot is shown. the x-axis is labeled hours spent practicing and the y-axis is labeled number of pieces student can play. data points are located at 1 and 1, 1 and 5, 2 and 10, 2 and 15, 3 and 15, 3 and 25, 4 and 40, 5 and 40, 5 and 50, 6 and 55, 6 and 70, 8 and 90, 3 and 70. a circle labeled t includes all points except for 3 and 70. point 3 and 70 is circled and labeled as r.

part a: what is the group of points labeled t called? what is the point labeled r called? give a possible reason for the presence of point r. (3 points)

part b: describe the association between the number of hours practiced each week and the number of pieces a piano student can play. (2 points)