Question

In a random sample of 13 residents of the state of Washington, the mean waste recycled per person per day was 1.6 pounds with a standard deviation of 0.43 pounds. Determine the 98% confidence interval for the mean waste recycled per person per day for the population of Washington.

Answer 1

We have given that,          
          
Sample mean =1.6 pounds  
Sample standard deviation =0.43 pounds
Sample size =13  
Level of significance=1-0.98=0.02  
Degree of freedom =12  
          
t critical value is (by using t table)=2.681  
          
Confidence interval formula is   

=(1.28,1.92)      
          
          
          
Lower confidence limit=   1.28 pounds  
          
Upper confidence limit=   1.92 pounds