Assumptions:  pg. 378

Use Student - t    
        1)  n < 30
        2)  Don't know   must use s
        3)  The parent population is essentially normal

Use Table A-3
        Degree of Freedom   n - 1
        p -   value  -  must use intervals as  t -tables are incomplete
                 (or use calculator for p-value)
 

Careful!!  Homework mixes  t 's  and  z 's
 

Find Critical t - values
            for hypothesis, sample sizes and   levels

#2
 
 
 
 

#8 TS:  t = -1.320;
    CV:  t = -2.718
 
 
 
 
 

 #14  Reject,  2-tailed
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 #20    **  n > 30;  so  z -test
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 #24   Using Raw data