differ according to the readers
11-13 An educator has the opinion that the grades high school students make depend on the amount
of time they spend listening to music. To test this theory, he has randomly given 400 students
a questionnaire. Within the questionnaire are the two questions: "How many hours per week
do you listen to music?" "What is the average grade for all your classes?" The data from the
survey are in the following table. Using a 5 percent significance level, test whether grades and
time spent listening to music are independent or dependent.
Hours Spent
Listening to Music
Average Grade
A
B
C
D
F
TOTAL
<5 hrs.
13
10
11
16
5
55
5-10 hrs.
20
27
27
19
2
95
11-20 hrs.
9
27
71
16
32
155
>20 hrs.
8
11
41
24
11
95
Total
50
75
150
75
50
400