What is a Confidence Interval

Question 1

For a confidence interval for a population parameter (e.g., the population mean) computed at a 96% confidence level, what proportion of all possible confidence intervals will contain the true parameter value? Enter answer with 2 decimal places.

Your Answer:

Hint for Question 1
The confidence interval is a function of a sample, which is random. So, confidence intervals are also random. Not all will contain the true parameter value. What does confidence level control? Question 2 With 80% confidence, for sample proportion 0.54 and sample size 24, what is the upper confidence limit with 2 decimal places? Your Answer: Question 3 Margin of Error - Mean Margin Mean What is the margin of error for the population mean at 90% confidence level for the information in DATA. (<--- Click the link to access the data for this problem.) Question 3 options: - 0.72 - 0.76 - 0.71 - 0.75 - 0.74 - 0.73 - None of the answers match my calculation. Hint for Question 3 Accuracy is required because three of the answers are close. Use Excel and click cells to enter cell addresses instead of typing intermediate results to avoid typing errors and loss of accuracy. Only round the final result using the Number options in the Excel's Home tab. You can use Excel Data Analysis, Descriptive Statistics. Take care to check the Labels check box if the Input Range includes the labels in row 2. Check boxes Summary statistics and Confidence Level for Mean. Update the confidence level to the value given in the question. Question 4 With 90% confidence, for sample mean 326.50, sample standard deviation 12.40, and sample size 35, what is the upper confidence limit with 2 decimal places? Your Answer: Question 5 Wait Time (minutes) 2.1 8.0 4.6 2.5 3.5 4.3 3.9 5.0 6.5 3.4 5.6 6.6 4.3 4.9 9.3 5.5 4.3 11.9 5.2 4.8 5.2 7.8 8.0 4.6 4.0 5.9 8.7 3.1 4.9 11.6 Bobo's Bad Burgers fast food claims you will be in and out in 5 minutes. To test this claim, time in minutes from entering Bobo's to receiving the order was secretly recorded. The results are documented in DATA. At a 95% confidence level, does the confidence interval support Bobo's claim? Question 5 options: - The confidence limits (1.62,3.21) reject the claim of 5 minutes. 5 is greater than the upper confidence limit. Performance at Bobo's is incredible. - None of the answers match my calculation. - The confidence limits (4.77,6.58) support the claim of 5 minutes. 5 falls in between the confidence limits. Bobo's performance meets the expectation. - The confidence limits (6.79,8.56) reject the claim of 5 minutes. 5 is less than the lower confidence limit. Audit of Bobo's procedures and employees is recommended. - The confidence limits (2.77, 4.54) reject the claim of 5 minutes. 5 is greater than the upper confidence limit. Bobo's performance is exemplary.