Breast cancer is strongly influenced by a woman's reproductive history. In particular, the longer the length of time from the age at menarche (the age when menstruation begins) to the age at first childbirth, the greater the risk is for breast cancer. A projection was made based on a mathematical model that the 30-year risk of a woman in the general U.S. population developing breast cancer from age 40 to age 70 is 7%. Suppose a special subgroup of five hundred six 40-year-old women without breast cancer was studied whose age at menarche was 17 (compared with an average age at menarche of 13 in the general population) and age at first birth was 20 (compared with an average age at first birth of 25 in the general population). These women were followed for development of breast cancer between ages 40 and 70. The study found that 17 of the women developed breast cancer between age 40 and age 70.

Express House Delivery Service provides high quality service to customers. The company guarantees a refund of all charges if a package it is delivering does not arrive at its destination by the specified time. It is known from past data that despite all efforts, 2% of the packages mailed through this company do not arrive at their destinations within the specified time. Suppose a corporation mails 10 packages through Express House Delivery Service on a certain day.

Is the national crime rate really going down? Some sociologists say yes! They say that the reason for the decline in crime rates in the 1980s and 1990s is demographics. It seems that the population is aging, and older people commit fewer crimes. According to the FBI and the Justice Department, 70% of all arrests are of males aged 15 to 34 years†. Suppose you are a sociologist in Rock Springs, Wyoming, and a random sample of police files showed that of 37 arrests last month, 22 were of males aged 15 to 34 years. Use a 10% level of significance to test the claim that the population proportion of such arrests in Rock Springs is different from 70%.

Age-related Macular Degeneration (AMD) is a common eye condition leading to vision loss. It causes damage to the macula, a small spot near the center of the retina (the part of the eye needed for sharp, central vision). Researchers are interested in the experiences of people who have been diagnosed with early-onset AMD. In particular the researchers are interested in whether the mean age at diagnosis of all people with early-onset AMD is less than 55 years. A random sample of 20 people with early-onset AMD gave the following data on age at diagnosis, in years. Patient 12 3 4 5 6 7 8 9 10 Age at diagnosis 50 58 52 58 49 58 51 61 54 59 Patient 11 12 13 14 15 16 17 18 19 20 Age at diagnosis 53 44 46 47 42 56 57 49 41 43 (d) State the conclusion of the test at the 5% level of significance. (e) Discuss why or why not an approximate normal test is appropriate here. (f) Perform an approximate normal test on the data at the 5% level. (g) Stating appropriate hypotheses perform the Student-t…

1. Pg 221 Good for the gut? Is fish good for the gut? Researchers tracked 22,000 male physicians for 22 years. Those who reported eating seafood of any kind at least 5 times per week had a 40% lower risk of colon cancer than those who said they ate seafood less than once a week. Based on this study, is it reasonable to conclude that eating seafood causes a reduction in the risk of colon cancer? Explain.44