Question

A corporation monitors time spent by office workers browsing the web on their computers instead of working. In a sample of computer records of 35 workers, the average amount of time spent browsing in an eight-hour work day was 53 minutes with standard deviation 11.6 minutes. Construct a 99% confidence interval for the mean number of hours the office workers spend browsing the web.

Report the answer accurate to four decimal places

< μμ <  

Answer 1

We have given that,          
          
Sample mean =53   minutes
Sample standard deviation =11.6 minutes
Sample size =35  
Level of significance=1-0.99=0.01  

          
Z critical value is (by using Z table)=   2.58
          
Confidence interval formula is

=>(47.9412,58.0588)
          
          
Lower confidence limit= 47.9412 minutes
          
Upper confidence limit=   58.0588 minutes