Question

A software developer wants to know how many new computer games people buy each year. A sample of 1233 people was taken to study their purchasing habits. Construct the 99% confidence interval for the mean number of computer games purchased each year if the sample mean was found to be 7.4. Assume that the population standard deviation is 1.4. Round your answers to one decimal place.

Answer 1

We have given that,                              
                              
Sample mean =7.4                      
Population standard deviation=1.4                  
Sample size=1233                      
Level of significance =   1-0.99=0.01                      
Z critical value (by using Z table)=2.58                  
                              
Confidence interval formula is


=(7.3,7.5)                              
                              
Lower confidence limit =7.3                  
Upper confidence limit =7.5