Question

Here are summary statistics for randomly selected weights of newborn girls: n=238, x= 30.7 hg, s=7.8 hg. Construct a confidence interval estimate of the mean. Use a 98% confidence level. Are these results very different from the confidence interval 28.6 hg<<33.2 hg with only 17 sample values, x= 30.9 hg, and s= 3.6 hg? What is the confidence interval for the population mean u? ng<u<ng (Round to one decimal place as needed.) Are the results between the two confidence intervals very different? O A. Yes, because the confidence interval limits are not similar. OB. No, because each confidence interval contains the mean of the other confidence interval. OC. Yes, because one confidence interval does not contain the mean of the other confidence interval. OD. No, because the confidence interval limits are similar.

Answer 1

sample mean 'x̄=		30.700
sample size    n=		238
std deviation s=		7.8000
std error ='sx=s/√n=7.8/√238=		0.5056

for 98% CI; and 237 df, value of t=		2.342
margin of error E=t*std error    =		1.184
lower bound=sample mean-E =		29.516
Upper bound=sample mean+E =		31.884
from above 98% confidence interval for population mean =(29.5 <μ< 31.9)

OB. No, because each confidence interval contains the mean of the other confidence interval.