<span>We have to use PEMDAS for this expression.
Parentheses
Exponents
Multiplication
Division
Addition
Subtraction
</span>(2x^2 - 5x + 4) Original Mathematical Expression
[2(7)^2 - 5(7) + 4] Plugging the value of x, 7 into expression.
There are parentheses, so that means we have to work in them.
There are exponents, so we have to do those first.
[2(49) - 5(7) +4] Exponents.
There is multiplication, that we can do, so we do that left to right.
[98 - 35 + 4] Multiplication.
There is no division.
There is addition and subtraction, so we do those left to right.
[63 + 4] Subtraction.
67 Addition.
Final Answer: 67
The answer is actually 80 degrees, I just took the test.
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
=====================================================
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.
----------------------------
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.