Question

Here are summary statistics for randomly selected weights of newborn girls: n= 176, x-28.5 hg, s = 7.2 hg. Construct a confidence interval estimate of the mean. Use a 90% confidence level. Are these results very different from the confidence interval 26.7 hg <p < 29.5 hg with only 16 sample values, x-281 hg, and s-3.1 hg? What is the confidence interval for the population mean μ? hg <p hg (Round to one decimal place as needed.)

Answer 1

Here n is sufficient large so we will use z distribution to find CI

z value for 90% CI is 1.645 as P(-1.645<z<1.645)=0.90

Hence Margin of Error is

E=…sn = 1.645 * v.176 7.2 = 1.645 *-= 0.9

Hence CI is

T± E 28.5 0.9 (27.6. 28.9)

So answer is

27.6ha < μ< 28.9hq

Yes it is different from

26.7 hg <p < 29.5 hg with only 16 sample values, x = 28.1 hg, and s = 3.1 hg