Review all student work for calculating a confidence interval for a sample mean. Redo their work and confirm that it is correct, or correct it and note the errors. What is the final margin of error E? What is the final confidence interval? Offer an example sample mean that would fit into the confidence interval. Offer an example sample mean that would be outside of the confidence interval.Review all student work for calculating a confidence interval for a sample proportion. Redo their work and confirm that it is correct, or correct it and note the errors. What is the final margin of error E? What is the final confidence interval? Offer an example sample proportion that would fit into the confidence interval. Offer an example sample proportion that would be outside of the confidence interval.

Student 1 post Stephanie

For this week I chose the dataset (exam scores), used the population of 30 (n = 30). Calculations for the mean confidence interval were straight-forward, to calculate a confidence interval proportion, I looked at exam scores above 90%. I started by sorting my data from the largest to smallest (note the student numbers are no longer sequential). For this small dataset, it was a simple matter to count 8 scores above 90%, and go from there. Finally, I rounded all calculations to 2 decimal places, because I found this easier.95% CI for mean: 76.59 90%: 0.11 90%) 90%13        84.0025        84.00 Observations                 822        82.00 Phat                               0.2723        82.0017        81.00 Error (proportion)         0.1618        80.001          77.00 LCI (proportion)           0.1111        77.00 UCI (proportion)           0.4228        77.0020        76.0016        73.003          71.0012        71.0021        71.0019        69.0027        65.0010        62.008          59.0026        59.00

Student 2 post Jennie 

My sample is: 31,34,54,32,34,37,47,37,47,54,34,54,38,32,31,30,43,54,23,21,32,34,36,54,32,37,32,34,35,34My sample mean is: 38My sample standard deviation: 9E=1.96(9)= 17.64Sqrt(30)= 5.47717.64/5.477

E=3.22Confidence Interval= 34.78 and 41.22

1.  My sample is:7,5,3,4,6,8,5,3,2,4,5,6,7,4,2,3,7,8,9,7,6,5,4,3,6,7,8,9,7,6,2.  My mean is: 63.  E=1.96* sqrt(6*(1-6)/30)= -.80           E= -.80          Confidence Interval= 5.2 and 6.8