Question

You must estimate the mean temperature (in degrees Fahrenheit) with the following sample temperatures:

18.2

15.9

25.1

8.4

24

18.9

21.9

18.3

18.1

Find the 90% confidence interval. Enter your answer as an open-interval (i.e., parentheses) accurate to two decimal places (because the sample data are reported accurate to one decimal place)

Answer 1

We have given that,          
          
Sample mean =18.76  
Sample standard deviation =4.9245
Sample size =9  
Level of significance=1-0.90=0.1  
Degree of freedom =8  
          
t critical value is (by using t table)=   1.86  
          
Confidence interval formula is   


=(15.71,21.81)      
          
          
          
Lower confidence limit=   15.71  
          
Upper confidence limit=   21.81