You are told that in a sample of size 225 the mean is 48.5 and the standard deviation is 1.8. The study is reported with 90% confidence level. Explain how to determine if 48.8 is within the confidence interval.

CL (%); 90, 95, 99

z*score:1.645, 1.96, 2.58

To find the margin of error, multiply the z-score by the standard deviation, then divide by the square root of the sample size.

The z*-score for a 90% confidence level is 1.645. The margin of error is 0.20.

The confidence interval is 48.3 to 48.7.

48.8 is not within the confidence interval.

To find the margin of error, multiply the z-score by the standard deviation, then divide by the square root of the sample size. The z*-score for a 90% confidence level is 1.645. The margin of error is 0.20. The confidence interval is 48.3 to 48.7.48.8 is not within the confidence interval.