In: Statistics and Probability
Construct the confidence interval for the population mean C equals 0.95, x overbar equals 16.6
S equals 8.0, and N equals 55
Solution :
Given that,
Point estimate = sample mean = = 16.6
sample standard deviation = s = 8.0
sample size = n = 55
Degrees of freedom = df = n - 1 = 55 - 1 = 54
At 95% confidence level the t is ,
= 1 - 95% = 1 - 0.95 = 0.05
/ 2 = 0.05 / 2 = 0.025
t /2,df = t0.025,54 = 2.005
Margin of error = E = t/2,df * (s /n)
= 2.005 * (8.0 / 55)
= 2.2
The 95% confidence interval estimate of the population mean is,
- E < < + E
16.6 - 2.2 < < 16.6 + 2.2
14.4 < < 18.8
(14.4 , 18.8)