Answer
a)   y    |      p(y)
     25   |      0.8
    100   |      0.15
    300   |      0.05
E(y) = ∑ y . p(y)
E(y) = 25 × 0.8 + 100 × 0.15 + 300 × 0.05
E(y) = 50
average class size equal to E(y) = 50
b)  y    |      p(y)
     25   |     
    100   |      
    300   |      
E(y) = ∑ y . p(y)
E(y) = 25 × 0.4 + 100 × 0.3 + 300 × 0.3
E(y) = 130
average class size equal to E(y) = 130
c) Average Student in the class in a school = 50
   Average student at the school has student = 130
 
        
             
        
        
        
Answer:
Please refer to the attached image.
 
        
             
        
        
        
Answer:
a square backyard with width (x - 9)
Step-by-step explanation:
x²−18x + 81 = x² - (2 x 9) x + 9² = (x - 9)²
width = area / length = (x - 9)² / (x - 9) = x - 9
Length = width
This is a square backyard
 
        
             
        
        
        
I think is B sorry if I am worng
        
             
        
        
        
Answer:
z' (-9,2)
Step-by-step explanation:
I recomend using desmos to show the relashinship
If you don't want to, thwn do this
Preimage
Since we are finding z, we only use the final cordinates
z'=(-9,2)