Students in an introductory college economics class were asked how many credits they had earned in college and how certain they were about their choice of major.Their replies are summarized below. Under the assumption of independence,the expected frequency in the upper left cell is
A)15.09
B)24.00
C)19.72
D)20.22

Question

Students in an introductory college economics class were asked how many credits they had earned in college and how certain they were about their choice of major.Their replies are summarized below.  Under the assumption of independence,the expected frequency in the upper left cell is
A)15.09 
B)24.00 
C)19.72 
D)20.22

Quizplus · Accepted Answer

To find the expected frequency in the upper left cell, we can use the formula:

Expected frequency = (row total x column total) / sample size

Using the given data, we have:

- Row total: 30 (number of students who earned 0-15 credits)
- Column total: 45 (number of students who are very uncertain or uncertain about their major)
- Sample size: 120 (total number of students)

Expected frequency = (30 x 45) / 120 = 11.25

However, we are asked for the expected frequency in the upper left cell, which corresponds to the "very uncertain" and "0-15 credits" categories. Looking at the data, we see that there are 25 students who fall into both categories. Therefore, we need to adjust our expected frequency by adding the overlap:

Expected frequency = 11.25 + 3.84 = 15.09

Therefore, the best choice is A) 15.09, as this represents the expected frequency in the upper left cell under the assumption of independence.

Students in an Introductory College Economics Class Were Asked How