in a law office the average number of billed hours per day w

in a law office, the average number of billed hours per day was 147 last year. In the first 67 days of this year, the average number of billed hours per day is 157 with a standard deviation of 59 hours. When testing the hypothesis (at the 10% level of signficance) that the average number of billed hours per day has increased, what crticial value? (please round your answer to 2 decimal places)

Solution

Formulating the null and alternative hypotheses,              
              
Ho:   u   <=   147  
Ha:    u   >   147  
              
As we can see, this is a    right   tailed test.      
              
Thus, getting the critical z, as alpha =    0.1   ,      
alpha =    0.1          
zcrit =    +1.28155156 = 1.28 [ANSWER]