MATH302 Week 5 Knowledge Check Homework Practice Questions

1. Question: Suppose a marketing company wants to determine the current proportion of customers who click on ads on their smartphones. It was estimated that the current proportion of customers who click on ads on their smartphones is 0.68. How many customers should the company survey in order to be 97% confident that the margin of error is 0.29 for the confidence interval of true proportion of customers who click on ads on their smartphones? 2. Question: There is no prior information about the proportion of Americans who support free trade in 2018. If we want to estimate a 97.5% confidence interval for the true proportion of Americans who support free trade in 2018 with a 0.16 margin of error, how many randomly selected Americans must be surveyed? 3. Question: Select the correct answer for the blank: If everything else stays the same, the required sample size ____ as the confidence level increases to reach the same margin of error. 4. Question: The population standard deviation for the height of college basketball players is 3.4 inches. If we want to estimate 95% confidence interval for the population mean height of these players with a 0.5 margin of error, how many randomly selected players must be surveyed? 5. Question: The population standard deviation for the height of college basketball players is 3.5 inches. If we want to estimate 97% confidence interval for the population mean height of these players with a 0.5 margin of error, how many randomly selected players must be surveyed? 6. Question: A random sample of college basketball players had an average height of 66.35 inches. Based on this sample, (65.6, 67.1) found to be a 94% confidence interval for the population mean height of college basketball players. Select the correct answer to interpret this interval. 7. Question: The population standard deviation for the height of college hockey players is 3.4 inches. If we want to estimate 90% confidence interval for the population mean height of these players with a 0.6 margin of error, how many randomly selected players must be surveyed? 8. Question: A recent study of 750 Internet users in Europe found that 35% of Internet users were women. What is the 95% confidence interval estimate for the true proportion of women in Europe who use the Internet? 9. Question: A teacher wanted to estimate the proportion of students who take notes in her class. She used data from a random sample of size n = 82 and found that 50 of them took notes. The 99% confidence interval for the proportion of student that take notes is: 10. Question: A teacher wanted to estimate the proportion of students who take notes in her class. She used data from a random sample of size n = 82 and found that 50 of them took notes. The 99% confidence interval for the proportion of student that take notes is: 11. Question: Suppose a marketing company computed a 94% confidence interval for the true proportion of customers who click on ads on their smartphones to be (0.56 , 0.62). Select the correct answer to interpret this interval 12. Question: The personnel department of a large corporation wants to estimate the family dental expenses of its employees to determine the feasibility of providing a dental insurance plan. A random sample of 12 employees reveals the following family dental expenses (in dollars). 13. Question: A sample of 9 production managers with over 15 years of experience has an average salary of $71,000 and a sample standard deviation of $18,000. Assuming that the salaries of production managers with over 15 years experience are normally distributed, you can be 95% confident that the mean salary for all production managers with at least 15 years of experience is between what two numbers. Place your LOWER limit, rounded to a whole number, in the first blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 54321 would be a legitimate entry.___. Place your UPPER limit, rounded to a whole number, in the second blank. Do not use a dollar sign, a comma, or any other stray mark. 14. Question: If a sample has 25 observations and a 99% confidence estimate for µ is needed, the appropriate value of the t-multiple required is___. Place your answer, rounded to 3 decimal places, in the blank. 15. Question: A sample of 40 country CD recordings of Willie Nelson has been examined. The average playing time of these recordings is 51.3 minutes, and the standard deviation is s = 5.8 minutes. Using an appropriate t-multiplier, construct a 95% confidence interval for the mean playing time of all Willie Nelson recordings. Place your LOWER limit, in minutes, rounded to 2 decimal places, in the first blank. For example, 56.78 would be a legitimate entry.___. Place your UPPER limit, in minutes, rounded to 2 decimal places, in the second blank. 16. Question: Select the correct answer for the blank: If everything else stays the same, the required sample size _____________ as the confidence level increases to reach the same margin of error. 17. Question: The amounts (in ounces) of randomly selected eight 16-ounce beverage cans are given below. 18. Question: It is known that the number of hours a student sleeps per night has a normal distribution. The sleeping time in hours of a random sample of 8 students is given below. See Attached Excel for Data. 19. Question: A random sample of stock prices per share (in dollars) is shown. Find the 90% confidence interval for the mean stock price. Assume the population of stock prices is normally distributed. 20. Question: A random sample of college football players had an average height of 64.55 inches. Based on this sample, (63.2, 65.9) found to be a 92% confidence interval for the population mean height of college football players. Select the correct answer to interpret this interval.