Chapter 8, Problem 8.28AC

Of the 1,000 people, 550 people used company s's smartphone and 460 people used company a's smartphone. Find a 95% confidence interval for the percentage of people using S company smartphones.

Wildlife biologists inspect 180 deer taken by hunters and find 36 of them carrying Lyme disease ticks. Calculate a 95% confidence interval for the proportion of deer that carry Lyme disease ticks.

A therapist wanted to determine if yoga or meditation is better for relieving stress. The therapist recruited 100 of her high-stress patients. Fifty of them were randomly assigned to take weekly yoga classes and the other 50 were assigned weekly meditation classes. After one month, 30 of the 50 patients in the yoga group reported less stress, and 35 of the 50 patients in the meditation group reported less stress. The therapist wants to construct a 95% confidence interval for the difference in proportions of patients experiencing stress relief after yoga and after meditation. Are the conditions for inference met? A) Yes, the conditions for inference are met. B) No, the 10% condition is not met. C) No, the randomness condition is not met. D) No, the Large Counts Condition is not met.

A researcher finds that individuals with a high school education or less are more likely to have hypertension than individuals with at least some college education.  They report a relative risk of 2.1 with a 95% confidence interval or (1.6, 2.5).  They then stratify their analysis by smoking status and report a relative risk of hypertension in smokers with a high school education or less as compared to smokers with at least some college education of 1.4 with a 95% confidence interval of (0.9, 1.9), and a relative risk of hypertension in non-smokers with a high school education or less as compared to non-smokers with at least some college education of 2.6 with a 95% confidence interval of (2.1, 3.2),  Which of the following is not true? A) there is effect modification by smoking status  B)  there is effect modification by hypertension status  C) there is no statistically significant assocation between education and hypertension amoung smokers  D) Education and hypertension are not…

In a clinical test with 2440 subjects, 70% showed improvement from the old treatment. While in a clinical test with another 2310 subjects, 75% showed improvement from the new treatment. Construct a 95% confidence interval to estimate the difference of the two population proportions.

A poll reported that only 507 out of a total of 1809 adults in a particular region said they had a​ "great deal of​ confidence" or​ "quite a lot of​ confidence" in the public school system. This was down 5 percentage points from the previous year. Assume the conditions for using the CLT are met.     Find a 95​% confidence interval for the proportion that express a great deal of confidence or quite a lot of confidence in the public​ schools, and interpret this interval.

In a study on drug use in the prison population carried out in 2006, it was found that 63% of inmates had consumed alcohol one month before entering prison. In a new survey of 4,985 inmates conducted in 2011, 3,227 reported having consumed alcohol in the 30 days prior to admission. Knowing that the population in 2011 was 71,387 individuals, we want to know with a confidence level of 98% if the percentage of inmates has suffered differences during the considered period. Calculate the p-value and interpret the value obtained