(solved) Math 225N Week 6 Assignment Confidence Interval for Mean
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Math 225N Week 6 Assignment Confidence Interval for Mean
Week 6 Assignment Confidence Interval for Mean
Question
Suppose scores of a standardized test are normally distributed and have a known population standard deviation of 11 points and an unknown population mean. A random sample of 15 scores is taken and gives a sample mean of 101 points. Find the confidence interval for the population mean with a 98% confidence level.
You may use a calculator or the common z values above.
Round the final answer to two decimal places
Provide your answer below:
Question
Suppose the scores of a standardized test are normally distributed. If the population standard deviation is 2 points, what minimum sample size is needed to be 90% confident that the sample mean is within 1 point of the true population mean?
Use the table above for the z-score, and be sure to round up to the nearest integer.
Provide your answer below:
Question
Suppose the heights of seasonal pine saplings are normally distributed. If the population standard deviation is 14 millimeters, what minimum sample size is needed to be 95% confident that the sample mean is within 4 millimeters of the true population mean?
Use the table above for the z-score, and be sure to round up to the nearest integer.
Provide your answer below:
Question
The length, in words, of the essays written for a contest are normally distributed with a population standard deviation of 442 words and an unknown population mean. If a random sample of 24 essays is taken and results in a sample mean of 1330 words, find a 99% confidence interval for the population mean.
You may use a calculator or the common z values above.
- Round the final answer to two decimal places.
Provide your answer below:
So we estimate with 99% confidence that the true population mean is between 1097.59 and 1562.41 words.
Question
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.
You may use a calculator or the common z values above.
- Round the final answer to two decimal places.
Provide your answer below:
Question
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:
We can estimate with 99% confidence that the true population mean length of adult corn snakes is between 53.88 and 62.12 inches.
We can estimate with 99% confidence that the sample mean length of adult corn snakes is between 53.88 and 62.12 inches.
We can estimate that 99% of adult corn snakes will have a length that is between 53.88 and 62.12 inches.
Question
The population standard deviation for the scores of a standardized test is 4 points. If we want to be 90% confident that the sample mean is within 1 point of the true population mean, what is the minimum sample size that should be taken?
Use the table above for the z-score, and be sure to round up to the nearest integer.
Provide your answer below:
Question
The population standard deviation for the total snowfalls per year in a city is 13 inches. If we want to be 95% confident that the sample mean is within 3 inches of the true population mean, what is the minimum sample size that should be taken?
Use the table above for the z-score, and be sure to round up to the nearest integer.
Provide your answer below: