Answer:
When it is small & when the sample has things that are different from the population.
Step-by-step explanation:
 A small sample has less chance of accurately reflecting a population & too many variables can also negatively influence the study. 
 
        
                    
             
        
        
        
Answer:
20/48
Step-by-step explanation:
 
        
                    
             
        
        
        
Want it exact? Here it is:499.243083(got it from my calculator), if rounded, then here it is:500
        
                    
             
        
        
        
Amount of tax paid = 43-40 = 3
Tax rate = 3/40 = 0.75
0.75 x 100 = 7.5%
Tax rate = 7.5%