In: Statistics and Probability
Assume you are provided the following 3 types of information and for each case you are assigned to calculate a 90% confidence interval around the sample mean. Answer the questions below based on the provided information.
Solution
Given that,
=125.5
=20.5
n = 40
At 90% confidence level the z is ,
= 1 - 90% = 1 - 0.90 = 0.10
/ 2 = 0.10 / 2 = 0.05
Z/2
= Z0.05 = 1.645
Margin of error = E = Z/2*
(
/n)
= 1.645 * (20.5 /
40 )
=5.3
At 90% confidence interval estimate of the population mean is,
- E <
<
+ E
125.5 - 5.3 <
< 125.5+ 5.3
120.2 <
< 130.8
(120.2 ,130.8)