Answers:
The z scores are approximately:
- Care of Magical Creatures:  z = 0.333
- Defense Against the Dark Arts:  z = 0.583
- Transfiguration:  z = -0.263
- Potions: z = -0.533
From those scores, we can say:
- Best grade = Defense Against the Dark Arts
- Worst grade = Potions
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Further Explanation:
We'll need to convert each given score to a corresponding standardized z score. 
The formula to use is 
z = (x - mu)/sigma
where,
- x = given grade for each class 
- mu = mean
- sigma = standard deviation
Let's find the z score for the Care of Magical Creatures class
z = (x - mu)/sigma
z = (3.80 - 3.75)/(0.15)
z = 0.333 approximately
Repeat this process for the Defense Against the Dark Arts score.
z = (x - mu)/sigma
z = (3.60 - 3.25)/(0.60)
z = 0.583 approximately
And for the Transfiguration class as well
z = (x - mu)/sigma
z = (3.10 - 3.20)/(0.38)
z = -0.263 approximately
The negative z score means his grade below the average, whereas earlier the other scores were above the average since he got positive z scores.
Now do the final class (Potions) to get this z score
z = (x - mu)/sigma
z = (2.50 - 2.90)/(0.75)
z = -0.533 approximately
This grade is below average as well.
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To summarize, we have these z scores
- Care of Magical Creatures:  z = 0.333
- Defense Against the Dark Arts:  z = 0.583
- Transfiguration:  z = -0.263
- Potions: z = -0.533
Harry did his best in Defense Against the Dark Arts because the z score of 0.583 (approximate) is the largest of the four z scores. On the other hand, his worst grade is in Potions because -0.533 is the lowest z score. 
 
        
             
        
        
        
Answer:
70
Step-by-step explanation:
100 - 2(x + 5) = 100 - 2x - 10 = 90 -2x
90 - 2x
90 - 2×10
90 - 20 = 70
 
        
                    
             
        
        
        
Step-by-step explanation:
Area of the Parallogram =bh
8√90=2✓5*h
12✓2=h
...................
 
        
                    
             
        
        
        
Answer:
   d) 27
Step-by-step explanation:
The expanded form of (a+b)³ is ...
   (a +b)³ = a³ +3a²b +3ab² +b³
When we are expanding (x +3)³, the x-term is ...
   3(x)(3²) = 27x
The coefficient of x in the expansion is 27.
 
        
             
        
        
        
Answer:
The areas of the squares adjacent to two sides of a right triangle are shown below.
  
  
What is the area of the square adjacent to the third side of the triangle?
 units^2  
2
Step-by-step explanation: