Answer:
3.06
Step-by-step explanation:
The correct answer is - 3.06
Reason -
For sample A :
mean,  = 8.05
 = 8.05          
Standard deviation,  = 1.36
 = 1.36          
Size,  = 50
 = 50          
                  
For sample B :
mean,  = 7.26
 = 7.26          
Standard deviation,  = 1.06
 = 1.06          
Size,  = 38
 = 38
Now,
 -
 -  = 8.05 - 7.26 = 0.79
  = 8.05 - 7.26 = 0.79
Standard deviation error, SE = √( ²/
²/ +
 +  ²/
²/ )  = 0.2580
)  = 0.2580
Now,
Z-statistic = ( -
 -  )/ SE
 )/ SE
                 = 0.79/0.2580 
                 = 3.06
⇒Z-statistic = 3.06
 
        
             
        
        
        
Answer:
a and c I'm 99percent shure