Answer:
there is a 15/80 chance  she will pick a black pen 
there is also a 65/80 chance she will pick a blue pen 
Step-by-step explanation:
 
        
             
        
        
        
15 students after dividing 825 with 55
        
                    
             
        
        
        
You just said that "the same number of people visited each day", 
so there's no "about" about it.  It has to be an exact number.
Each day,  (2744)/(14) = 196 people visited. 
        
                    
             
        
        
        
Area=pi times radius^2 so 
if area=4pi=pi times r^2
4 times pi=r^2 times pi
divide both sdies by pi
4=r^2
square root
2=radius since legnth cannot be negative
radius=1/2 diamters
2 radius=diameter
2(2)=diameter=4
diameter=4