The Ball Corporations beverage can manufacturing plant in Fo

The Ball Corporation\'s beverage can manufacturing plant in Fort Atkinson, Wisconsin, uses a metal supplier that provides metal with a known thickness standard deviation = 0.000821 mm. Assume a random sample of 45 sheets of metal resulted in an 1formula131.mml = 0.1503 mm. Calculate the 90 percent confidence interval for the true mean metal thickness. (Round your answers to 4 decimal places.) The 90% confidence interval is from, to?

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 =    0.05          
X = sample mean =    0.1503          
z(alpha/2) = critical z for the confidence interval =    1.64          
s = sample standard deviation =    0.000821          
n = sample size =    45          
              
Thus,              
Margin of Error E =    0.000200715          
Lower bound =    0.150099285          
Upper bound =    0.150500715          
              
Thus, the confidence interval is              
              
(   0.150099285   ,   0.150500715   ) [ANSWER]