A consumer group conducted a study regarding the number of hours of TV that teenagers watched per week. The cumulative frequencies of the sample were as follows.

Hours per week Cumulative Frequency

0-4 ................ 7

5-9 ............... 25

10-14 .............. 49

15-19 .............. 77

20-24 ............. 120

What is the mean "weekly hours of TV watched" for the sample?

a.) .38

b.) 12

c.) 15.42

d.) 17

e.) 370