Last school year, the student body of a local university consisted of 30% freshmen, 24% sophomores, 26% juniors, and 20% seniors.A sample of 400 students taken from this year's student body showed the following number of students in each classification. We are interested in determining whether or not there has been a significant change in the classifications between the last school year and this school year.The expected frequency of seniors is
A) 120.
B) 96.
C) 80.
D) 74.

Question

Last school year, the student body of a local university consisted of 30% freshmen, 24% sophomores, 26% juniors, and 20% seniors.A sample of 400 students taken from this year's student body showed the following number of students in each classification.  ​ We are interested in determining whether or not there has been a significant change in the classifications between the last school year and this school year.The expected frequency of seniors is
A) 120. 
B) 96. 
C) 80. 
D) 74.

Quizplus · Accepted Answer

We know that last year, 20% of the student body were seniors. If we assume that the total number of students has stayed the same from last year to this year, then we can expect that 20% of this year's sample of 400 students would be seniors.

Expected frequency of seniors = (20/100) * 400 = 80

Last School Year, the Student Body of a Local University