Question

If n=13, ¯ x x¯ (x-bar)=50, and s=16, 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.

< μ <

Answer 1

Solution :

degrees of freedom = n - 1 = 13 - 1 = 12

t/2,df = t0.10,12 = 1.356

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

= 1.356 * (16 / 13)

Margin of error = E = 6.0

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

- E < < + E

50 - 6.0 < < 50 + 6.0

44.0 < < 56.0