If we assume the average number of teeth lost in the 5−9 group is 7 teeth and the average number of teeth lost in the 10+ group is 12 teeth, what is the best estimate of the average number of teeth lost per year?

Dentistry
The data in Table 4.20 were reported by men in the Health Professionals Follow-up Study on the number of teeth lost over a 1-year period (January 1, 1987, to December 31, 1987).

Table 4.20: Distribution of number of teeth lost from January 1, 1987, to December 31, 1987, among 38,905 men in the Health Professionals Follow-up Study

Number of teeth lost ___________________ Frequency
0 ....................................................................... 35,763
1 ..........................................................................1,978
2 ............................................................................ 591
3 ............................................................................ 151
4 ............................................................................ 163
5−9 ........................................................................ 106
10+ ........................................................................ 153
Total ................................................................ 38,905