# 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.

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 11 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Fall
Professor
N/A
Tags
Taylor Swift