Answer: (14.18, 15.08)
Step-by-step explanation:
Given : Sample size : n= 64
Sample mean : [tex]\overline{x}=15[/tex]
Standard deviation : [tex]\sigma=4[/tex]
Significance level : [tex]\alpha: 1-0.90=0.1[/tex]
Critical value : [tex]z_{\alpha/2}=1.645[/tex]
The confidence interval for population mean is given by :-
[tex]\overline{x}\pm\ z_{\alpha/2}\dfrac{\sigma}{\sqrt{n}}\\\\=15\pm(1.645)\dfrac{4}{\sqrt{64}}\\\\\approx15\pm0.82\\\\=(14.18,\ 15.08)[/tex]
Hence, the 90% confidence interval for the population mean of waiting times is (14.18, 15.08).
