statistics
posted by AMY .
Consider a 95% confidence interval for a population mean constructed from a random sample of 250 observations taken from a Normal population. Sigma is known to be 14. If we were to construct another 95% confidence interval, this time using 1,000 observations, how would the length of this interval compare to the length of the original interval?

the sample of selected men have the average weight of 180lb with the standard deviation of 30lb. for 0.95 find the confidence interval for the mean of the whole population