Answer:
17. 20  
18. 50
19. 50
20. 70
21. 110
22. 160
Step-by-step explanation:
 I did this assignment already :)
 
        
             
        
        
        
Answer:
Systematic sampling 
Step-by-step explanation:
An EPA contractor needing to test the concentration of a substance in ten samples out seventy samples provided form a single source at regular time intervals. 
For the contractor to effectively carry out the testing he has to employ a Non-probability system of sampling which is called Systematic sampling, because in systematic sampling we can assume the population size (x ) which in this case is 70 and the sample size( n ) to be 10 
He will have to select ;  ( x / n )^th of the sampling frame for best results 
 
        
             
        
        
        
Answer:
C
Step-by-step explanation:
If you look closely.. You can see that one is longer than the other
 
        
             
        
        
        
Is that a triangle prism? Sorry I'm bad at shapes but I can do the area if I know what shape it is
        
                    
             
        
        
        
Are you doing online school? I am and i need this as well :(