Question

If n=32, (x-bar)=39, and s=17, construct a confidence interval at a 80% confidence level. Assume the data came from a normally distributed population. Give your answers to one decimal place.

Answer 1

Solution :

Given that,

t /2,df = 1.309

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

= 1.309 * (17 / 32)

Margin of error = E = 3.9

The 80% confidence interval estimate of the population mean is,

- E < < + E

39 - 3.9 < < 39 + 3.9

35.1 < < 42.9

(35.1 , 42.9)