Answer:
[tex]CI =0.894%[/tex]
Step-by-step explanation:
From the question we are told that:
Sample size [tex]n=4[/tex]
Standard deviation [tex]\sigma=0.76\% of \=x[/tex]
Confidence level [tex]\mu =90\%=0.90[/tex]
Degree of Freedom [tex]Df=n-1=3[/tex]
Therefore
Test T from table is given
 [tex]t=2.353[/tex]
Generally the equation for Confidence interval CI is mathematically given by
 [tex]CI =t*\frac{\sigma}{\sqrt{n}}[/tex]
 [tex]CI =2.353*\frac{0.76}{\sqrt{4}}[/tex]
 [tex]CI =0.894%[/tex]
