<Dl> <Dd> Lower endpoint = X _̄ − 1.96 σ n, (\ displaystyle (\ text (Lower endpoint)) = (\ bar (X)) - 1.96 (\ frac (\ sigma) (\ sqrt (n))),) </Dd> </Dl> <Dd> Lower endpoint = X _̄ − 1.96 σ n, (\ displaystyle (\ text (Lower endpoint)) = (\ bar (X)) - 1.96 (\ frac (\ sigma) (\ sqrt (n))),) </Dd> <P> and the upper endpoint of the 95% confidence interval is: </P> <Dl> <Dd> Upper endpoint = X _̄ + 1.96 σ n . (\ displaystyle (\ text (Upper endpoint)) = (\ bar (X)) + 1.96 (\ frac (\ sigma) (\ sqrt (n))).) </Dd> </Dl>

What does it mean to have a 90 confidence interval