If y = 12 and x = 6, using an indirect variation, what is the value of y when x = 20?
When two variables change in inverse proportion it is called an indirect variation. In an indirect variation, one variable is constant times inverse of the other. If one variable increases other will decrease, if one decreases other will also increase. This means that the variables change in the same ratio but inversely.
The general equation for an inverse variation is y = k / x. Or k = xy which is constant. So the product of two variables is a constant for inverse variation.
y = 12 x = 6
y = k / x
12 = 72 / 6
Now we can calculate the value of y when x = 20
y = 72 / x
y = 72 / 20
y = 3.6