95 Confidence Interval Sample Size 30. N ge 30 n 30 sample mean is normally distributed. But it might not be.
When the sample size was increased from 20 to 200 the confidence interval became more narrow. Degree of freedom 30 -1 29. This says the true mean of ALL men if we could measure all their heights is likely to be between 1688cm and 1812cm.
For the lower interval score divide the standard error by the square root on n and then multiply the sum of this calculation by the z-score 196 for 95.
StatKey was used to construct a 95 confidence interval using the percentile method. Since the sample size is large we can use the formula that employs the Z-score. The difference was the sample size. The confidence level is 95.
