How healthy are the employees at Direct Marketing Industry A

How healthy are the employees at Direct Marketing Industry? A random sample of 12 employees was taken, and the number of days each was absent tor sickness was recorded (for a 1-year period). Use these data to create a 95% confidence interval tor the population mean days absent for sickness. You can use SPSS to help you. 2.87 days to 7.29 days 3.28 days to 6.89 days 3.11 days to 7.05 days 2.77 days to 7.39 days 2.87 days to 5.08 days

Solution

5.

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 =    5.083333333          
t(alpha/2) = critical t for the confidence interval =    2.20098516          
s = sample standard deviation =    3.476108936          
n = sample size =    12          
df = n - 1 =    11          
Thus,              
              
Lower bound =    2.874719086          
Upper bound =    7.291947581          
              
Thus, the confidence interval is              
              
(   2.87   ,   7.29   ) [ANSWER, A]