Questions:
1) A random sample is to be selected from a population with mu = 100 and standard deviation = 10. Determine the standard deviation of the x-bar sampling distribution for a sample size of n = 9. (three decimal places)
2) A random sample is to be selected from a population with mu = 100 and standard deviation = 10. Determine the standard deviation of the x-bar sampling distribution for a sample size of n = 400. (three decimal places)
3) Suppose that a random sample of size 64 is to be selected from a population with mean 40 and standard deviation 5.
What is the standard deviation of the sampling distribution?
4) Suppose that a random sample of size 64 is to be selected from a population with mean 40 and standard deviation of 5.
What is the approximate probability that xbar will be within .5 of the population mean mu? (round to 4 decimal places)
5) Suppose that a random sample of size 64 is to be selected from a population with mean 40 and standard deviation of 5.
What is the approximate probability that xbar will differ from mu by more than .7? (4 decimal places please)
6) In the library on a university campus, there is a sign in the elevator that indicates a limit of 16 persons. Further more, there is a weight limit of 2500 pounds. Assume the average weight of students, faculty and staff on campus is 150 pounds, the standard deviation is 27 pounds and that the distribution is approximately normal, If a random sample of 16 persons from the campus is taken
What is the expected value of the sample mean of their weights?
7) In the library on a university campus, there is a sign in the elevator that indicates a limit of 16 persons. Further more, there is a weight limit of 2500 pounds. Assume the average weight of students, faculty and staff on campus is 150 pounds, the standard deviation is 27 pounds and that the distribution is approximately normal. If a random sample of 16 persons from the campus is taken.
8)What is the standard deviation of the sampling distribution?
9) In the library on a university campus, there is a sign in the elevator that indicates a limit of 16 persons. Further more, there is a weight limit of 2500 pounds. Assume the average weight of students, faculty and staff on campus is 150 pounds, the standard deviation is 27 pounds and that the distribution is approximately normal, If a random sample of 16 persons from the campus is taken.
What average weight for these 16 people will result in the total weight exceeding the weight limit of 2500 pounds. (two decimal places)
10) In the library on a university campus, there is a sign in the elevator that indicates a limit of 16 persons. Further more, there is a weight limit of 2500 pounds. Assume the average weight of students, faculty and staff on campus is 150 pounds, the standard deviation is 27 pounds and that the distribution is approximately normal, If a random sample of 16 persons from the campus is taken
What is the chance that a random sample of 16 persons on the elevator will exceed the weight limit? (four decimal places)
11) Use the pull out table(Z-TABle) in your book and list the critical value (z*) for a 95% confidence Interval (two decimal places).
12) Using your z table and a graph of a normal curve, calculate the z* value for an 88% confidence interval
13) Using the student's t table, find the critical value (t*) for a sample of 21 students with a confidence interval of 98%
14) A medical researcher from the National Institute of Health has collected samples on the life expectancies of people who are long-time smokers and those who are nonsmokers. The sample data is summarized in the table below.
Group sample size sample mean standard deviation
smokers 50 67.6 5
nonsmokers 60 74.6 3.5
15) A medical researcher from the National Institute of Health has collected samples on the life expectancies of people who are long-time smokers and those who are nonsmokers. The sample data is summarized in the prev table. Compute a 95% confidence interval for the mean life expectancy of a smoker.
16) Compute a 95% confidence interval for the mean life expectancy of a nonsmoker using prev table
17) A study of the price of a gallon of heating oil reported the following statistics from random samples of prices on the east coast and the west coast#
Coast sample size sample mean sample standard deviation
east 90 1.096 .035
west 160 1.123 .036
18) Compute a 95% confidence interval for the mean price of a gallon of heating oil on the east coast from prev table
19)Compute a 95% confidence interval for the mean price of a gallon of heating oil on the west coast.