Question

Here are summary statistics for randomly selected weights of newborn​ girls: n=212​, x bar=31.5

hg, s=7.5 hg. Construct a confidence interval estimate of the mean. Use a 99​% confidence level. Are these results very different from the confidence interval 29.5 hg <μ<34.134.1 hg with only 16 sample​ values, x bar=31.8 hg, and s=3.1 hg?

hg <μ< HG

Answer 1

Solution :

degrees of freedom = n - 1 = 212 - 1 = 211

t/2,df = 2.599

Margin of error = E = t/2,df * (s /n)

= 2.599 * ( 7.5 / 212)

Margin of error = E = 1.3

The 99% confidence interval estimate of the population mean is,

   - E < < + E

31.5 - 1.3 < < 31.5 + 1.3

30.2 < < 32.8

Yes, because the confidence interval limits are not similar