1. Construct the confidence interval for the population mean?
c=0.95, x(samplemean) =16.1, s=8.0, and n=90
A 95% confidence interval for ? is ?
2. Use the confidence interval to find the margin of error and the sample mean.
(0.282, 0.420)
The margin of error is?
The sample mean is?
3. People were polled on how many books they read the previous year. How many subjects are needed to estimate the number of books read the previous year within one book 90% confidence? Initial survey results indicate that ?=18.4 books.
A 90% confidence level requires ? subjects.
4. In a random sample of 42 bolts, the mean length was 1.51 inches and the standard deviation was 0.08 inch. Use a normal t-distribution or a t-distribution to construct a 90% confidence interval for the mean.
The 90% confidence interval is?