1. In a random sample of 24 people, the mean number of books they had read in the past year was 11.22 books and the standard deviation was 16.60 books. Assume the variable is normally distributed and use a t-distribution to construct a 95% confidence interval for the population mean . What is the margin of error of ?
(Round to nearest hundredth.)
2. A researcher wishes to estimate, with 95% confidence, the proportion of adults who have high-speed Internet access. Her estimate must be accurate within 1% of the true proportion,
a) Find the minimum sample size needed, using a prior study that found that 38% of the respondents said they have high-speed Internet access. (Round to nearest whole number.)
b) No preliminary estimate is available. Find the minimum sample size needed.
3. About 72% of all female heart transplant patients will survive for at least 3 years. 60 female heart transplant patients are randomly selected. What is the probability thst sample proportion surviving for at least 3 years will be less than 67%? Assume that the sampling distribution of sample proportions is a normal distribution.