Answer:
lower limit : 36.44
upper limit : 39.56
Step-by-step explanation:
Given :
s = 9
n = 90
x = 38.9
Alpha, α = 0.10
∴ [tex]$z_{\alpha/2}=z_{0.05} = 1.645$[/tex]
The confidence interval is :
[tex]$=x \pm\left(z_{\alpha /2} \times \frac{s}{\sqrt{n}}\right)$[/tex]
[tex]$=38.9 \pm\left(1.645 \times \frac{9}{\sqrt{90}}\right)$[/tex]
[tex]$=38.9 \pm 1.56$[/tex]
[tex]$=(36.44, 39.56)$[/tex]
Therefore,
lower limit : 36.44
upper limit : 39.56
