1. Use the confidence interval to find the margin of error and the sample mean. (0.178,0.380)

2.Find the minimum sample size n needed to estimate μ for the given values of? c, σ?, and E.

c=0.95

σ=5.2and

E=11

Assume that a preliminary sample has at least 30 members

3.Use the confidence interval to find the estimated margin of error. Then find the sample mean.

A biologist reports a confidence interval of (3.1,3.7) when estimating the mean height? (in centimeters) of a sample of seedlings

Margin of error=?

Sample mean=?

4.You are given the sample mean and the population standard deviation. Use this information to construct the? 90% and? 95% confidence intervals for the population mean. Which interval is? wider? If? convenient, use technology to construct the confidence intervals.A random sample of 31 gas grills has a mean price of ?$642.40Assume the population standard deviation is ?$59.20

The? 90% confidence interval is?

5.A random sample of forty-six ?200-meter swims has a mean time of 3.37minutes and the population standard deviation is 0.09 minutes. Construct a 90?% confidence interval for the population mean time.

6.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 with 99?% ?confidence? Initial survey results indicate that σ=18.9 books

7.A doctor wants to estimate the HDL cholesterol of all? 20- to? 29-year-old females. How many subjects are needed to estimate the HDL cholesterol within 22 points with 99% confidence assuming σ=16.8?  Suppose the doctor would be content with 90% confidence. How does the decrease in confidence affect the sample size? required?

8.In a random sample of 21?people, the mean commute time to work was 32.2minutes and the standard deviation was 7.2 minutes. Assume the population is normally distributed and use a? t-distribution to construct a 98?% confidence interval for the population mean μ.

What is the margin of error of μ?? Interpret the results.