In: Statistics and Probability
Solution :
Given that,
sample mean =
= 192
Population standard deviation =
= 104
Sample size = n =30
At 90% confidence level the z is ,
= 1 - 90% = 1 - 0.90 = 0.1
/ 2 = 0.1 / 2 = 0.05
Z/2 = Z0.05 = 1.645 ( Using z table )
Margin of error = E = Z/2
* (
/n)
= 1.645* ( 104/ 30
)
= 31.23
At 90% confidence interval
is,
- E <
<
+ E
192 - 31.23 <
< 192 + 31.23
160.77 <
< 223.23
( 160.77 , 223.23)