The class sizes of the introductory psychology courses at a college are shown below 121,134,106,93,149,130,119,128 the college adds a new honors introductory psychology course with 45 student. What effect does the new class size have on the center and spread of the class sizes of the introductory psychology courses at the college?

Center : Mean  Before the introduction of the new course, center = average(121,134,106,93,149,130,119,128) = 122.5  After the introduction of the new course, center =  average(121,134,106,93,149,130,119,128,45) = 113.9  The center has moved to the left (if plotted in a graph) because of the low intake for the new course.  Spread before introduction of the new course :  Arrange the numbers in ascending order:  (93, 106,119, 121), (128, 130,134, 149) Q1=median(93,106,119,121) = 112.5 Q3=median(128,130,134,149) = 132  Spread = Interquartile range = Q3-Q1 = 19.5  After addition of the new course,

 (45,93, 106,119,) 121, (128, 130,134, 149)
 Q1=median(45,93,106,119)=99.5
 Q3=median (128, 130,134, 149)= 132
 Spread = Interquartile range = 132-99.5 =32.5 
 We see that the spread has increased after the addition of the new course.