Answer: 25
Step-by-step explanation:
Given : Level of confidence = 0.90
Significance level : [tex]\alpha=1-0.90=0.10[/tex]
Critical value : [tex]z_{\alpha/2}=1.645[/tex]
Margin of error : [tex]E=\text{ 1 days}[/tex]
Standard deviation: [tex]\sigma=\text{ 3 day}[/tex]
The formula to find the sample size : [tex]n=(\dfrac{z_{\alpha/2}\sigma}{E})^2[/tex]
[tex]n=(\dfrac{(1.645)(3)}{1})^2=24.354225\approx25[/tex]
Hence, the minimum sample size needed= 25.
