Suppose dental practice improves over the 30-year period. We assume the rate of tooth loss per year from 1987−2001 (15 years) is the same as in 1987, whereas the rate of tooth loss per year from 2002−2016 (15 years) is half the 1987 rate. What is the probability that the man in Problem 4.87 will require dentures under these altered assumptions?

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