Question

Suppose y varies directly as x. If y=-4 when x = 32, find x when y=-0.375.

Answer 1

If y varies directly with x, we have a relation that is:

$y=kx$

where k is a constant.

If we know a point, we can find the constant as:

$k=\frac{y}{x}=\frac{-4}{32}=-0.125$

Now we have to calculate x for y=-0.375:

$\begin{gathered} y=kx \\ x=\frac{y}{k}=\frac{-0.375}{-0.125}=3 \end{gathered}$

The value for x is 3.