1. Question: Suppose the germination periods, in days, for grass seed are normally distributed. If the population standard deviation is 3 days, what minimum sample size is needed to be 90% confident that the sample mean is within 1 day of the true population mean?
2. 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.
3. 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.

4. 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?

5. 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?
6. Question: The weights, in pounds, of dogs in a city are normally distributed with a population standard deviation of 2 pounds and an unknown population mean. A random sample of 16 dogs is taken and results in a sample mean of 28 pounds.

Identify the parameters needed to calculate a confidence interval at the 90% confidence level. Then find the confidence interval.

7. Question: The weights, in pounds, of dogs in a city are normally distributed with a population standard deviation of 2 pounds and an unknown population mean. A random sample of 16 dogs is taken and results in a sample mean of 28 pounds.

What is the correct interpretation of the confidence interval?

8. Question: Suppose heights of dogs, in inches, in a city are normally distributed and have a known population standard deviation of 7 inches and an unknown population mean. A random sample of 15 dogs is taken and gives a sample mean of 34 inches. Find the confidence interval for the population mean with a 99% confidence level.
9. Question: The germination periods, in days, for grass seed are normally distributed with a population standard deviation of 5 days and an unknown population mean. If a random sample of 17 types of grass seed is taken and results in a sample mean of 52 days, find a 80% confidence interval for the population mean.
10. Question: Suppose scores of a standardized test are normally distributed and have a known population standard deviation of 6 points and an unknown population mean. A random sample of 22 scores is taken and gives a sample mean of 92 points.

Identify the parameters needed to calculate a confidence interval at the 98% confidence level. Then find the confidence interval.

11. Question: Suppose scores of a standardized test are normally distributed and have a known population standard deviation of 6 points and an unknown population mean. A random sample of 22 scores is taken and gives a sample mean of 92 points.

What is the correct interpretation of the 95% confidence interval?

12. 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?
13. 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?
14. 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?
15. Question: The population standard deviation for the lengths, in seconds, of the songs in an online database is 15 seconds. If we want to be 90% confident that the sample mean is within 4seconds of the true population mean, what is the minimum sample size that should be taken?
16. Question: The population standard deviation for the number of corn kernels on an ear of corn is 94 kernels. If we want to be 90% confident that the sample mean is within 17 kernels of the true population mean, what is the minimum sample size that should be taken?
17. Question: Suppose the weights, in pounds, of the dogs in a city are normally distributed. If the population standard deviation is 3 pounds, what minimum sample size is needed to be 95% confident that the sample mean is within 1 pound of the true population mean?
18. Question: Suppose the number of dollars spent per week on groceries is normally distributed. If the population standard deviation is 7 dollars, what minimum sample size is needed to be 90% confident that the sample mean is within 3 dollars of the true population mean?
19. Question: Suppose the speeds of vehicles traveling on a highway are normally distributed. If the population standard deviation is 2 miles per hour, what minimum sample size is needed to be 90% confident that the sample mean is within 1 mile per hour of the true population mean?
20. Question: A College Board sample estimated the standard deviation of 2016 SAT scores to be 194 points. You are researching the average SAT score. You want to know how many people you should survey if you want to know, at a 98% confidence level, that the sample mean SAT score is within 50 points of the true mean SAT score. What value for z should you use in the sample size formula? 
21. Question: You are researching the average SAT score, and you want to know how many people you should survey if you want to know, at a 98% confidence level, that the sample mean score is within 50 points of the true population mean. From above, we know that the population standard deviation is 194, and z0.01=2.326. What is the minimum sample size that should be surveyed? ​
22. Question: A television network wants to estimate the average number of hours of TV watched each week by viewers.  The network decides to create a 95% confidence interval for the average number of hours of TV watched each week.  How large of a sample size of viewers should be used to create this confidence interval if the television network wants to be 95% confident that the sample mean is within 1 hour of the population mean?  Assume the standard deviation for the number of hours of TV watched each week is 5. 97 viewers
23. Question: Suppose the number of square feet per house is normally distributed. If the population standard deviation is 155 square feet, what minimum sample size is needed to be 90% confident that the sample mean is within 47 square feet of the true population mean?
24. Question: The population standard deviation for the typing speeds for secretaries is 4 words per minute. If we want to be 90% confident that the sample mean is within 1 word per minute of the true population mean, what is the minimum sample size that should be taken?
25. Question: The population standard deviation for the body weights of the employees of a company is 10 pounds. If we want to be 95% confident that the sample mean is within 3 pounds of the true population mean, what is the minimum sample size that should be taken?
26. Question: The population standard deviation for the scores of a standardized test is 5 points. If we want to be 95% confident that the sample mean is within 2 points of the true population mean, what is the minimum sample size that should be taken?
27. Question: Suppose the scores of a standardized test are normally distributed. If the population standard deviation is 4 points, what minimum sample size is needed to be 95% confident that the sample mean is within 1 point of the true population mean?
28. Question: The population standard deviation for the lengths, in words, of the essays written for a contest is 542 words. If we want to be 90% confident that the sample mean is within 141 words of the true population mean, what is the minimum sample size that should be taken?
29. Question: Suppose the total snowfalls per year in a city are normally distributed. If the population standard deviation is 13 inches, what minimum sample size is needed to be 95% confident that the sample mean is within 4 inches of the true population mean?
30. Question: 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?
31. Question: The population standard deviation for the number of pills in a supplement bottle is 16 pills. If we want to be 95% confident that the sample mean is within 5 pills of the true population mean, what is the minimum sample size that should be taken?