In developing an interval estimate for a population mean, a sample of 50 observations was used. the interval estimate was 19.76 ± 1.32. had the sample size been 200 instead of 50, the interval estimate would have been:

The formula for interval estimate would be: μ = M ± Z (sM)

Where: μ is estimate

M is the mean

Z is the z value

(sM) is the standard error

μ = M ± Z (sM)

n = 200 rather than 50 (√200 = 2√50)

⇒ ME = (1/2) * 1.32 =.66

Using the formula above, plugging this in will give us: μ = 19.76 ±.66

= 19.76 ±.66 is the confidence interval or interval estimate