In an effort to find a method of predicting the dental work required by army recruits, an army dentist studies the dental records of a random sample of 10 recruits completing their service. She computes the relationship between the number of cavities filled in the first two years of service y with the number of cavities filled in the two years before service x.

Suppose the following statistics are computed for the dental study in Exercise 9.3.3: Ex = 50, Ly = 52, _xy = 321 E(x- 3)2 -68, (-9) = 75.6 a. Find the estimate of the slope of the trend line. b. Find the standard error of the estimate of the slope. c. Find 95% central confidence intervals for: i. The slope of the trend line. ii. The average number of cavities an enlistee will have filled during his first two years of service. d. Find the 95% prediction interval for the number of cavities to be filled in the teeth of a new enlistee who in the previous two years had 3 new fillings