Question1,

A simple random sample of size n=40 is drawn from a population. The sample mean is found to be x=121.9

and the sample standard deviation is found to be s=12.8.

Construct a 99% confidence interval for the population mean.

The lower bound is?

Questions 2,

A survey was conducted that asked 1018 people how many books they had read in the past year. Results indicated that

x=10.8 books and s=16.6 books.

Construct a 99% confidence interval for the mean number of books people read. Interpret the interval.

Question 3,

A simple random sample of size n is drawn from a population that is normally distributed. The sample mean, x, is found to be

112, and the sample standard deviation, s, is found to be 10.

(a) Construct a 90% confidence interval about if the sample size, n, is 21.

(b) Construct a 90% confidence interval about if the sample size, n, is 16.

(c) Construct an 80% confidence interval about if the sample size, n, is 21.

(d) Could we have computed the confidence intervals in parts (a)-(c) if the population had not been normally distributed?