Question

Noise levels at 6 airports were measured in decibels yielding the following data: 137,132,145,152,209,169

Construct the 80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal.

Step 3 of 4 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

Step 4 of 4: Construct the 80% confidence interval. Round your answer to one decimal place. Lower endpoint Upper endpoint

Answer 1

We have for given data,          
          
Sample mean =157.33  
Sample standard deviation =28.43
Sample size =6  
Level of significance=1-0.80=0.2  
Degree of freedom =       5  
          
t critical value is (by using t table)=   1.476
          
Confidence interval formula is


=(140.2,174.5)
      
          
          
          
Lower confidence limit=   140.2  
          
Upper confidence limit=   174.5