Question

The quantities of x and y are proportional. Find the constant of proportionality (r) in the equation y= rx

Answer 1

All you have to do is choose one of the rows, and then substitute in the values for x and y into the equation y = rx, and then solve for r:

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I'll choose the first row, where x = 8  when y = 2:

$y=rx$    (substitute in, x = 8  and y = 2)

$2=r\times8$    (divide both sides by 8)

$\frac{2}{8}=r$    (simplify the fraction)

$\frac{1}{4}=r$    (Change to a decimal)

$0.25 = r$

So

$r=0.25$

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Answer:

$r=0.25$