Answer:
Lower bound of 90% confidence interval: 26.04
Upper bound of 90% confidence interval: 26.96
Step-by-step explanation:
We are given the following in the question:
Sample mean, [tex]\bar{x}[/tex] = 26.5
Sample size, n = 652
Population standard deviation, σ = 7.2
90% Confidence interval:
[tex]\mu \pm z_{critical}\frac{\sigma}{\sqrt{n}}[/tex]
Putting the values, we get,
[tex]z_{critical}\text{ at}~\alpha_{0.05} = 1.645[/tex]
[tex]26.5 \pm 1.645(\frac{7.2}{\sqrt{652}} ) = 26.5 \pm 0.4638 =(26.0362,26.9638) \approx (26.04,26.96)[/tex]