a Provide a 90 confidence interval for the population mean

Last updated: 11/16/2023

a Provide a 90 confidence interval for the population mean Recall that a confidence interval is calculated using the sample mean and a margin of error The margin of error will vary depending on the level of confidence a the population standard deviation o and the size of the sample n This value will be added to and subtracted from the sample mean x using the following formula where Za 2 is the value of z that gives an area of z a in the upper tail of the standard normal probability distribution 2 6 V n below x a 2 The value of a is found by setting the confidence level equal to 1 a and solving for a Here we have 1 a 0 90 so a 0 10 and 2 Confidence Level a 90 95 99 O NA a 2 za 2 0 10 0 05 1 645 0 05 0 025 1 960 0 01 0 005 2 576 For a 90 confidence level the necessary value for z a 2 N is Common values for z 2 are given