Question 109031
In 1990 the percentage of children living with two parents was 72.5 and in 2002 it was 68.7 
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(a.) Assuming that the decrease was linear, write and equation relating the percentage y and the year x, with 1980 corresponding to x=0.
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You have two points relating year and percentage: (10,72.5) & (22,68.7)

slope = [68.7-72.5]/[2002-1990] = -3.8/12= -1.9/6
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72.5 = (-1.9/6)(10)+b
b = 72.5+3.166667
b = 75.666667
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EQUATION:
y = (-1.9/6)x + 75.666667
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(b.) Graph the equation for the years 1990-2010.
{{{graph(400,300,-10,30,-10,80,(-1.9/6)x+75.6666667)}}}
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(c.) Estimate the precentage of children living in two parent families in 2010.
y = (-1.9/6)(30) + 75.66666667 
y = 66.17%
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Cheers,
Stan H.