(ANSWER) MATH 225N-Week 6 Assignment Confidence Interval for Mean Population Standard Deviation Known
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Question1
Suppose finishing time for cyclists in a race are normally distributed and have a known population standard deviation of 6 minutes and an unknown population mean. A random sample of 18 cyclists is taken and gives a sample mean of 146 minutes.
Find the confidence interval for the population mean with a 99% confidence level.
| z0.10z0.10 | z0.05z0.05 | z0.025z0.025 | z0.01z0.01 | z0.005z0.005 |
|---|---|---|---|---|
| 1.282 | 1.645 | 1.960 | 2.326 | 2.576 |
You may use a calculator or the common z values above.
- Round the final answer to two decimal places.
Provide your answer below:
Question 2
The number of square feet per house are normally distributed with a population standard deviation of 154 square feet and an unknown population mean. If a random sample of 16 houses is taken and results in a sample mean of 1550 square feet, find a 80% confidence interval for the population mean.
| z0.10z0.10 | z0.05z0.05 | z0.025z0.025 | z0.01z0.01 | z0.005z0.005 |
|---|---|---|---|---|
| 1.282 | 1.645 | 1.960 | 2.326 | 2.576 |
You may use a calculator or the common z values above.
- Round the final answer to two decimal places.
Provide your answer below:
Question 3
Suppose the finishing times for cyclists in a race are normally distributed. If the population standard deviation is 16 minutes, what minimum sample size is needed to be 90% confident that the sample mean is within 5 minutes of the true population mean?
Use the table above for the z-score, and be sure to round up to the nearest integer.
Question 4
Suppose the finishing times for cyclists in a race are normally distributed. If the population standard deviation is 16 minutes, what minimum sample size is needed to be 90% confident that the sample mean is within 5 minutes of the true population mean?
Use the table above for the z-score, and be sure to round up to the nearest integer.
Question 5
The lengths, in inches, of adult corn snakes are normally distributed with a population standard deviation of 8 inches and an unknown population mean. A random sample of 25 snakes is taken and results in a sample mean of 58 inches.
Identify the parameters needed to calculate a confidence interval at the 99% confidence level. Then find the confidence interval.
| z0.10z0.10 | z0.05z0.05 | z0.025z0.025 | z0.01z0.01 | z0.005z0.005 |
|---|---|---|---|---|
| 1.282 | 1.645 | 1.960 | 2.326 | 2.576 |
You may use a calculator or the common z values above.
- Round the final answer to two decimal places.
Provide your answer below:
Question 6
The lengths, in inches, of adult corn snakes are normally distributed with a population standard deviation of 8 inches and an unknown population mean. A random sample of 25 snakes is taken and results in a sample mean of 58 inches.
What is the correct interpretation of the confidence interval?
Select the correct answer below:
