Find the area under the normal curve to the left of zequalsnegative 2 plus the area under the normal curve to the right of zequals2.
Find the area under the normal curve to the left of zequalsnegative 1.53 plus the area under the normal curve to the right of zequals2.53.
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 equals 18.7 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 blank subjects.
The decrease in the confidence level will also decrease the required sample size (from 258 to 150 subjects, if confidence level is decreased from 99% to 95%
A survey was conducted that asked 953 people how many books they had read in the past year. Results indicated that x =14.3 books and s =15.8 books. Construct a 98‹% confidence interval for the mean number of books people read. Interpret the interval.