Question

A psychologist is collecting data on the time it takes to learn a certain task. For 50 randomly selected adult subjects, the sample mean is 16.40 minutes and the sample standard deviation is 4.00 minutes. Construct the 95% confidence interval for the mean time required by all adults to learn the task.

Answer 1

We have given that,          
          
Sample mean =16.4  
Sample standard deviation =4
Sample size =50  
Level of significance=0.05  
Degree of freedom =49  
          
t critical value is (by using t table)=   2.0096  
          
Confidence interval formula is   

=(15.26,17.54)  
          
          
          
Lower confidence limit=   15.26  
          
Upper confidence limit=   17.54