Answer:
[tex]\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}[/tex] (1)
The confidence interval for this case would be:
[tex] 100 \leq \mu \leq 120[/tex]
And we want to know what happens with the interval if we reduce the confidence level to 90% and for this case we will get a narrower interval since the critical value [tex]t_{\alpha/2}[/tex] would be lower. So then the best option would be:
a. becomes narrower
Step-by-step explanation:
Notation
[tex]\bar X[/tex] represent the sample mean for the sample
[tex]\mu[/tex] population mean
s represent the sample standard deviation
n represent the sample size
Solution
The confidence interval for the mean is given by the following formula:
[tex]\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}[/tex] (1)
The confidence interval for this case would be:
[tex] 100 \leq \mu \leq 120[/tex]
And we want to know what happens with the interval if we reduce the confidence level to 90% and for this case we will get a narrower interval since the critical value [tex]t_{\alpha/2}[/tex] would be lower. So then the best option would be:
a. becomes narrower
