Question

2.3.2: Michael Myers predicts that SAT scores predict college graduation rates in a linear fashion. U of M has an average SAT of 1450 and a graduation rate of 90%. GVSU has an average SAT of 1110 and a graduation rate of 69.6%. Write an equation to represent the linear relationship . Be sure your equation is in slope-intercept form

Answer 1

Answer:

$y = \frac{5000r}{3} -50$

Step-by-step explanation:

Represent the SAT score with y and the rate with r.

So, we have:

$(r_1,y_1) = (90\%,1450)$

$(r_2,y_2) = (69.6\%,1110)$

Required

Determine the equation in slope intercept form

First, we calculate the slope

$m =\frac{y_2 - y_1}{r_2 - r_1}$

This gives:

$m =\frac{1110 - 1450}{69.6\% - 90\%}$

$m =\frac{-340}{-20.4\%}$

Convert percentage to decimal

$m =\frac{-340}{-0.204}$

$m =\frac{340}{0.204}$

Multiply by 1000/1000

$m =\frac{340*1000}{0.204*1000}$

$m =\frac{340000}{204}$

$m = \frac{5000}{3}$

The equation is then calculated as:

$y - y_1 = m(r - r_1)$

This gives:

$y - 1450 = \frac{5000}{3}(r - 90\%)$

Open Bracket

$y - 1450 = \frac{5000r}{3} - \frac{5000}{3}*90\%$

Convert percentage to decimal

$y - 1450 = \frac{5000r}{3} - \frac{5000}{3}*0.90$

$y - 1450 = \frac{5000r}{3} - 5000*0.30$

$y - 1450 = \frac{5000r}{3} - 1500$

Make y the subject

$y = \frac{5000r}{3} - 1500+1450$

$y = \frac{5000r}{3} -50$