Let x refers to the Month numbers
And y refers to Number of births
There is 5 steps to find the quadratic function that models the data.
First step ⇒ <span>Plot <span>the data pairs (<span>x<span>, <span>y<span>) in a coordinate plane.
which are the blue circles in the attached figure
Second step ⇒ </span></span></span></span></span></span><span>Draw <span>the parabola you think best fits the data.
Which is the red function in the attached figure.
</span></span><span><span>Third step ⇒</span> Estimate <span>the coordinates of three points on the
<span> parabola, which are (2, 108), (4, 68), and (6, 75).</span>
</span></span><span><span>which are the black squares in the attached figure</span>
Fourth step ⇒ </span><span>Substitute <span>the coordinates of the points into the<span> model <span>
y <span>= <span>ax<span>2 <span>+ <span>bx <span>+ <span>c
<span> to obtain a system of three linear equations.</span>
4a + 2 b + c = 108 ---------(1)
</span></span></span></span></span></span></span></span></span></span></span><span><span>16a + 4 b + c = 68 ---------(2)</span>
36a + 6 b + c = 75 ---------(3)
Fifth step ⇒ </span><span>Solve <span>the linear system.
By using the calculator
a = 5.875 , b = -55.25 , c = 195
So, the</span></span><span> quadratic model for the data is ⇒ y = 5.875 x²- 55.25 x + 195
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T</span><span>o predict the number of births for month 8
substitute with x = 8 ⇒ y = </span><span>5.875 * 8²- 55.25 * 8 + 195 = 129</span>
