Question 1203121

The sample mean symbol is x̄, pronounced “x bar”. 

{{{ n=10}}} 
​
 
x̄={{{ 26.1}}} 

{{{ s=4.2}}} 
​

Two-sided confidence interval {{{CI}}} :


​{{{  df=n-1=10-1=9}}} 

{{{  alpha=1-0.99=0.01}}} 

{{{  Z[c_(alpha/2)]=Z[c(0.005)]=3.2498=3.25}}} 



{{{ CI}}}= (x̄-{{{ Z[c]*s/sqrt(n)}}}, x̄+{{{ Z[c]*s/sqrt(n)}}}) 


{{{CI}}}= ({{{26.1-(3.25*4.2)/sqrt(10)}}},{{{ 26.1+(3.25*4.2)/sqrt(10)}}})


{{{CI}}}= ({{{26.1-4.3}}}, {{{26.1+4.3}}})


{{{CI}}}= ({{{21.8}}}, {{{30.4}}})



{{{99}}}% confidence interval:


{{{21.8 <CI < 30.4}}}