3. A researcher is studying how long people live as a function of the average nu

Question

3. A researcher is studying how long people live as a function of the average number of cigarettes they smoked per day at age 30. Assume the data collected are appropriate for studying this question. She finds the following means and standard deviations from her sample of 102 males. She develops the following regression equation to predict age at death from average number of cigarettes smoked per day at age 30:y'- 82-60x Mean Standard Deviation Average # of cig/day at 30 | 10 Age of Death76 15 a) Suppose a 30-year-old man who smokes 2 packs a day (there are 20 cigarettes in a pack) asks the researcher to predict the age at which he will die. What age would the researcher predict? (10 pts) b) What is the proportion of variance in age of death which is linearly predictable from knowing the average number of cigarettes smoked per day at age 30? (6 pts) c) What is the probability that a person who smokes a pack a day at age 30 will live past 85? (13 pts)

Explanation / Answer

a) predicted age of dying for x=2*20=40 cigarettes is =82-0.60*40=58

b)

proportion of variance =R2 =(b1*Sx/Sy)2 =((-0.60)*15/12)2 =0.5625

c)

from normal distribution:

P(X>85)=P(Z>(85-76)/12)=P(Z>0.75)=0.2266

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.