Question

Construct the confidence interval for the population mean μ.

c=0.90, x overbar=15.3 ,σ=9.0and n=85

A 90​% confidence interval for μ is ___,___?
Round to one decimal place as​ needed.)

Answer 1

Solution :

Given that,

= 15.3

= 9.0

n = 85

c = 0.90

At c = 0.90 confidence level the z is ,

= 1 - c = 1 - 0.90 = 0.10

/ 2 = 0.10 / 2 = 0.05

Z_/2 = Z_0.05 = 1.645

Margin of error = E = Z_/2* ( /n)

= 1.645 * (9.0 / 85)

= 1.6

At 90% confidence interval estimate of the population mean is,

- E < < + E

15.3 - 1.6 < <15.3 + 1.6

13.7< <16.9

(13.7,16.9 )