Question

A geologist examines 1717 sedimentary samples for magnesium concentration. The mean magnesium concentration for the sample data is 0.4880.488 cc/cubic meter with a standard deviation of 0.04180.0418. Determine the 80%80% confidence interval for the population mean magnesium concentration. Assume the population is approximately normal.

Step 1 of 2 :

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

Answer 1

We have given that,              
              
Sample mean =0.488      
Sample standard deviation =0.0418  
Sample size =17      
Level of significance=1-0.80=0.2      
Degree of freedom =16      
              

t critical value is (by using t table)=1.337

              
Confidence interval formula is               


=(0.4744,0.5016)          
              
              
Lower confidence limit=0.4744      
              
Upper confidence limit=0.5016