In: Statistics and Probability
Q7. Here are summary statistics for randomly selected weights of newborn girls: n=210, x overbarx=28.9 hg, s=6.3hg. Construct a confidence interval estimate of the mean. Use a 99% confidence level. Are these results very different from the confidence interval 27.0 hgless than
What is the confidence interval for the population mean muμ?
____hgless than
std dev , s = 6.3000
Sample Size , n = 210
Sample Mean, x̅ = 28.9000
Level of Significance , α =
0.01
' ' '
z value= z α/2= 2.5758 [Excel
formula =NORMSINV(α/2) ]
Standard Error , SE = s/√n = 6.300 /
√ 210 = 0.4347
margin of error, E=Z*SE = 2.5758
* 0.435 = 1.120
confidence interval is
Interval Lower Limit = x̅ - E = 28.90
- 1.120 = 27.7802
Interval Upper Limit = x̅ + E = 28.90
- 1.120 = 30.0198
99% confidence interval is ( 27.8
< µ < 30.0 )