I just want to make sure that I did these right so 1) 1. A survey of 430 randoml
ID: 2959216 • Letter: I
Question
I just want to make sure that I did these right so1) 1. A survey of 430 randomly chosen adults found that 21% of the 222 men and 18% of the 208 women had purchased books online. Is there evidence that men are more likely than women to make online purchases of books? Investigate this question with a 95% confidence interval.
2 proportion confidence interval (2propZint on the calc)
2)2. In 1960, census results indicated that the age at which American men first married had a mean of 23.3 years. It is widely suspected that young people today are waiting longer to get married. We want to find out if the mean age of first marriage has increased during the past 50 years. A random sample of 40 men who married for the first time last year was selected. The men in the sample married at an average age of 24.2 years with a standard deviation of 5.3 years. Does this information support the theory that men are waiting longer to get married than they did in 1960? Investigate this question with a 95% confidence interval.
2 prop z interval (on the calc)
3. In 2003, the Journal of the American Medical Association reported a study examining the possible impact of air pollution caused by the 9/11 attack on New York’s World Trade Center on the weight of babies. Researchers found that 8% of 182 babies born to mothers who were exposed to heavy doses of soot and ash of September 11 were classified as having low birth weight. Only 4% of 2300 babies born in another New York City hospital whose mothers had not been near the site of the disaster were similarly classified. Does this indicate a possibility that air pollution might be linked to a significantly higher proportion of low birth weight babies? Investigate this question with a hypothesis test. Use a = 0.05.
2 mean hypothesis test (T test?)
4. Consumer Reports tested 14 brands of vanilla yogurt and found these numbers of calories per serving: 160, 130, 200, 170, 220, 190, 230, 80, 120, 120, 180, 100, 140, 170. A diet guide claims that you will get 120 calories from a serving of vanilla yogurt. What does this evidence indicate? Investigate this question with a hypothesis test. Use a = 0.05.
T test (?)
I would really appreciate it if one could just check that I was using the right type of test.
Explanation / Answer
(1) You are right.
(2)2 mean z interval
(3)2 proportion hypothesis z test
(4) You are right.