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Confidence Interval Practice- due 4/29

Last updated over 1 year ago
8 questions
6
Connecticut is located between New York and Boston, so baseball fans in the state typically root for either the Yankees or Red Sox. In a recent poll of 803 randomly selected baseball fans in Connecticut, 44% said their favorite team was the Yankees.
Construct a 95% confidence interval for the proportion of all baseball fans in Connecticut who would say their favorite team is the Yankees: DO:
Is this a confidence interval for a proportion or mean? _______
What is the critical value you need to use, z* or t*? _______
What is the z critical you need to use? _______
What is the margin of error? _______ round to three places past the decimal
Lower bound of the confidence interval = _______ round to 3 places
Upper bound of the confidence interval = _______ round to 3 places
Required
4

Based on the interval, is it plausible that the Yankees are the favorite team for a majority of Connecticut baseball fans?
Explain by choosing the correct answers.

Required
6
Melissa and Madeline love pepperoni pizza, but sometimes they are disappointed with the small number of pepperonis on their pizza. To investigate, they went to their favorite pizza restaurant at 10 random times during the week and ordered a large pepperoni pizza. She found an average of 37.4 slices and a standard deviation of 7.662 pepperoni slices a. Construct a 95% confidence interval for the true mean number of pepperonis on a large pizza at this restaurant: DO
Is this a confidence interval for a proportion or mean? _______
What is the critical value you need to use, z* or t*? _______
What is the t critical value from the chart? _______
What is the margin of error?_______ round to three places past the decimal
Lower bound of the confidence interval = _______ round to 3 places
Upper bound of the confidence interval = _______ round to 3 places
Required
3

According to the manager of the restaurant, there should be an average of 40 pepperonis on a large pizza. Based on the interval, is there convincing evidence that the average number of pepperonis is less than 40?
Explain by choosing the correct answers.

Required
6
The Pew Research Center’s Teen Relationship Survey found that 33% of 929 randomly selected teens with cell phones use messaging apps.
Calculate a 95% confidence interval for the proportion of all teens with cell phones who use messaging apps. DO:
Is this a confidence interval for a proportion or mean? _______
What is the critical value you need to use, z* or t*? _______
What is the z critical value from the chart? _______
What is the margin of error?_______ round to four places past the decimal
Lower bound of the confidence interval = _______ round to 4 places
Upper bound of the confidence interval = _______ round to 4 places
Required
3

Based on the interval, if Meredith did a study at DHS and found that 36 out of 82 students use messaging apps, do her results give convincing evidence that the study by the PRC might be incorrect? Explain by selecting the appropriate answers.

Required
6
Mr. Wilcox has done over 50 track days at Gingerman Raceway in South Haven Michigan. He keeps track of each lap time (in seconds) and has found that they follow an approximately normal distribution. A random sample of 9 laps shows a mean laptime of 102.4 seconds with a standard deviation of 3.2 seconds. Create a 90% confidence interval for Mr. Wilcox’s career average lap time. DO:
Is this a confidence interval for a proportion or mean? _______
What is the critical value you need to use, z* or t*? _______
What is the t critical value from the chart? _______
What is the margin of error?_______ round to 3 places past the decimal
Lower bound of the confidence interval = _______ round to 3 places
Upper bound of the confidence interval = _______ round to 3 places
Required
3

If the next weekend Mr. Wilcox tries a new brand of tires and completes the a lap in 99.6 seconds, is this convincing evidence that the tires are better than the brand he has always used? Explain by selecting the appropriate answers.