Question

What is the direct linear variation equation for the relationship?

y varies directly with x and y = 4 when x = 12.

A.
y = x – 8

B.
y = x + 8

C.
y = 1/3x

D.
y = 3x

Answer 1

Direct variation is of the form y=kx.  We are given a point (12,4) so we can solve for the constant of variation...

4=12k  divide both sides by 12

1/3=k 

So the equation is:

y=x/3  or as your choices says the equivalent

y=(1/3)x