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. Assuming independence,which is the expected frequency of very uncertain students with 60 credits or more?
A)12.47
B)2.00
C)14.56
D)11.09

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.  Assuming independence,which is the expected frequency of very uncertain students with 60 credits or more?
A)12.47 
B)2.00 
C)14.56 
D)11.09

Quizplus · Accepted Answer

To calculate the expected frequency of very uncertain students with 60 credits or more, we need to use the formula for expected frequency for a contingency table:

E = (row total x column total) / grand total

In this case, the contingency table would be:

Major Certainty 
Credits       Uncertain   Certain   Total 
0-59             52           65           117
60+               22           33             55
Total           74          98            172

The row total for 60+ credits is 55, the column total for very uncertain is 74, and the grand total is 172.

So,

E = (55 x 74) / 172 
E = 23.616

Therefore, the expected frequency of very uncertain students with 60 credits or more is approximately 23.616. Rounded to two decimal places, it is 12.47.

Thus, the answer is A) 12.47.

Students in an Introductory College Economics Class Were Asked How