# Calculate the 99 confidence interval for the true

• 11
• 89% (53) 47 out of 53 people found this document helpful

This preview shows page 7 - 9 out of 11 pages.

2)Calculate the 99% confidence interval for the true population mean for the BMIdata. Recall that the new sample contains 15 people and has a mean of 25.97kg/m2and a standard deviation of 7.10 kg/m2.Because our sample has fewer than 30 cases, we cannot assume that the distribution ofsample means will be normal, and must use the t-distribution. The margin of error isbased on the significance level (1-confidence level, or 1-0.99=0.01), the standarddeviation (in B2) and the sample size (in B3).We can compute the margin of error usingthe Excel function CONFIDENCE.T(0.01,B2,B3). The lower bound of the 99%confidence interval is the sample mean minus the margin of error, that is B1–CONFIDENCE.T(0.01,B2,B3)= 25.97-5.46=20.51. The upper bound of the 99%confidence interval is the sample mean plus the margin of error, that isB1+CONFIDENCE.T(0.01,B2,B3)= 25.97+5.46=31.43. We can be 99% confident thatthe true mean BMI of all U.S. citizens is between 20.51 kg/m2and 31.43 kg/m2. You mustlink directly to cells to obtain the correct answer.
3)Calculate the 80% confidence interval for the true population mean based on asample withx¯=225, s=8.5, and n=45.

Course Hero member to access this document

Course Hero member to access this document

End of preview. Want to read all 11 pages?

Course Hero member to access this document

Term
Fall
Professor
N/A
Tags
Taylor Swift
• • • 