Practice Set 4

1. Find z for each of the following confidence levels. Round to two decimal places.

1. 90%
2. 95%
3. 96%
4. 97%
5. 98%
6. 99%

2. For a data set obtained from a random sample, n = 81 and x = 48.25. It is known

that σ = 4.8.

1. What is the point estimate of μ? Round to two decimal places
2. Make a 95% confidence interval for μ. What is the lower limit? Round to two decimal places.
3. Make a 95% confidence interval for μ. What is the upper limit? Round to two decimal places.
4. What is the margin of error of estimate for part b? Round to two decimal places.

3. Determine the sample size (nfor the estimate of μ for the following.

1. E = 2.3, σ = 15.40, confidence level = 99%. Round to the nearest whole number.
2. E = 4.1, σ = 23.45, confidence level = 95%. Round to the nearest whole number.
3. E = 25.9, σ = 122.25, confidence level = 90%. Round to the nearest whole number.

4. True or False.

a.The null hypothesis is a claim about a population parameter that is assumed to be false until it is declared false.