Answer:
Step-by-step explanation:
Given : Level of significance :
Then , significance level :
Since , sample size : , which is small sample (n<30) so the test applied here is a t-test.
Sample mean :
Standard deviation:
Degree of freedom=
Using t-distribution table , Critical value :
The confidence interval for population mean is given by :-
Hence, a 90% confidence interval for the population mean=