# If z varies inversely as w, and z=10 when w=0.6, how do you find z when w=20?

Mar 24, 2018

$z = 0.3$

#### Explanation:

When working with variance (proportion) - either direct or inverse, you need the find the value of the constant first.

$z \propto \frac{1}{w} \text{ } \rightarrow z = \frac{k}{w}$

$k = w \times z$

$k = 0.6 \times 10 = 6 \text{ }$ use the given values to find $k$

$\therefore z = \frac{6}{w} \text{ "or" "w=6/z" "or" } w z = 6$

Now $\text{ } z = \frac{6}{20}$

$z = \frac{6}{20} = \frac{3}{10} = 0.3$