<span>The vertex form of a quadratic is given by. y = a(x – h)2 + k, where (h, k) is the vertex. The "a" in the vertex form is the same "a" as. in y = ax2 + bx + c (that is, both a's have exactly the same value). The sign on "a" tells you whether the quadratic opens up or opens down.</span><span>
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Solution: The correct option is d. 8.75
<u>Explanation:</u>
The formula for variance is:
First we need to find the mean of the given data:
Now let's find , please have a look at the attached picture:
7/8=0.875
0.875 x 40= 35
Therefore, Kris has finished 35 questions.
Hope this helps.
The curve has been attached and the answer choices are:
y = 3x² – 2x + 1
y = 3x² – 6x + 3
y = 3x²<span> – 7x + 1
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The attached graph has a vertex in the first quadrant. Therefore, the coordinates of the vertex would be both positive.
Let's start with first equation:
y = 3x² – 2x + 1
using the equation of axis:
x = -b/2a
x = 2/6
x = 1/3
SUbstituting the value of x in the main equation to get the y-coordinate of the vertex.
y = 3(1/3)² – 2(1/3) + 1
y = 3/9 – 2/3 + 1
y = 1/3 – 2/3 + 1
y = (1 - 2 + 3)/3
y = 2/3
Hence, the vertex would be:
(h,k) = (1/3 , 2/3)
Also, the leading coefficient is positive, so the parabola would be concave up.
Thus the final answer choice will be:
y = 3x² – 2x + 1