A health organization is concerned about possible mercury co

A health organization is concerned about possible mercury contamination in a large city\'s water supply. They take a random sample of 30 people in this city and give them a blood test, measuring the level of mercury in their blood. The find a mean level of 43, with a standard deviation of 24. Report the 95% confidence interval for mu

Solution

Note that              
Margin of Error E = z(alpha/2) * s / sqrt(n)              
Lower Bound = X - z(alpha/2) * s / sqrt(n)              
Upper Bound = X + z(alpha/2) * s / sqrt(n)              
              
where              
alpha/2 = (1 - confidence level)/2 =    0.025          
X = sample mean =    43          
z(alpha/2) = critical z for the confidence interval =    1.959963985          
s = sample standard deviation =    24          
n = sample size =    30          
              
Thus,              
Margin of Error E =    8.58813189          
Lower bound =    34.41186811          
Upper bound =    51.58813189          
              
Thus, the confidence interval is              
              
(   34.41186811   ,   51.58813189   ) [ANSWER]