Listed below are measured amount of lead in micrograms per c
     Listed below are measured amount of lead (in micrograms per cubic meter, or mug/m^3) in the EPA has  an air quality stand red mug/m^3. The measurements shown below were recorded at a building on different days.  What is the confidence interval for the population moan mu? 
  
  Solution
Note that              
               
 Lower Bound = X - t(alpha/2) * s / sqrt(n)              
 Upper Bound = X + t(alpha/2) * s / sqrt(n)              
               
 where              
 alpha/2 = (1 - confidence level)/2 =    0.025          
 X = sample mean =    1.633333333          
 t(alpha/2) = critical t for the confidence interval =    2.570581836          
 s = sample standard deviation =    1.869006866          
 n = sample size =    6          
 df = n - 1 =    5          
 Thus,              
               
 Lower bound =    -0.328069083          
 Upper bound =    3.59473575          
               
 Thus, the confidence interval is              
               
 (   -0.328069083   ,   3.59473575   ) [ANSWER]

