Question

A market research company wishes to know how many energy drinks adults drink each week. They want to construct a 98% confidence interval for the mean and are assuming that the population standard deviation for the number of energy drinks consumed each week is 1.3. The study found that for a sample of 1133 adults the mean number of energy drinks consumed per week is 7.1 . Construct the desired confidence interval. Round your answers to one decimal place. Lower endpoint? Upper endpoint?

Answer 1

We have given that,          
          
Sample mean =7.1  
Population standard deviation=1.3
Sample size=1133  
Level of significance =1-0.98=0.02  
Z critical value (by using Z table)=2.326  
          
Confidence interval formula is          


=(7.01,7.19)      
Lower confidence limit =7.0
Upper confidence limit =7.2