1. A doctor wants to estimate the mean HDL cholesterol of all 20-to 29 year old females. How many subjects are needed to estimate the mean HDL cholesterol within 3 points with 99% confidence assuming s=16.1 based on earlier studies? Suppose the doctor would be content with 95% confidence. how does the decrease in confidence affect the sample size required?
A 99% confidence level requires how many subjects? Round up to the nearest subject
A 95% confidence level requires how many subjects? Round up to the nearest subject.
2 People were polled on how many books they read the previous year. Initial survey results indicate that s=11.1 books. Complete parts (a) through (c) below.
(a) How many subjects are needed to estimate the mean number of books read the previous year within six books with 90% confidence? This 90% confidence levels requires how many subjects? Round up to the nearest subject.
(b) How many subjects are needed to estimate the mean number of books read the previous year within three books with 90% confidence? This 90% confidence level requires how many subjects? Round up to the nearest subject
(c) How many subjects are needed to estimate the mean number of books read the previous year within six books with 99% confidence? This 99% confidence level requires how many subjects? Round up to the nearest subject
3. Base on interviews with 95 SARS patients' researchers found that the mean incubation period was 5.6 days, with a standard deviation of 14.5 days. Based on this information, construct a 95% confidence interval for the mean incubation period of the SARS virus. Interpret the interval.
The lower bound is how many days? Round to two decimal places as needed
The upper bound is how many days? Round to two decimal places as needed
4. A researcher wishes to estimate the percentage of adults who support abolishing the penny. What size sample should be obtained if he wishes the estimate to be within 4 percentage points with 90% confidence if (a) he uses previous estimate of 36%? ,,(b) he does not use any prior estimates?
(a) n = ? round up to the nearest integer.
(b) n = ? round up to the nearest integer.
5. In a trial of 213 patients who received 10-mg doses of a drug daily,34 reported headache as a side effect.
(a) Obtain a point estimate for the population proportion of patients who received 10-mg doses of a drug daily and reported headache as a side effect, ^p=?