Question

Select the correct answer.

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 students. 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?

A. The value of the center increases and the distribution has a larger spread.
B. The value of the center decreases and the distribution has a smaller spread.
C. The value of the center decreases and the distribution has a larger spread.
D. The value of the center increases and the distribution has a smaller spread.

Answer 1

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.