Question

If y varies inversely as x and y = 320 when x = 25, how do you find y when x is 40?

Answer 1

`y=200`.

Explanation:

If `y` is inversely as `x`, it means that it exists an equation like

`y=k/x` where `k` is a constant.

We know that when `x=25`, `y=320`, so we have

`320=k/25`. From here we can calculate `k` as

`k=320*25=8000`.

Then the equation is

`y=8000/x`.

We can now calculate `y=8000/40=200`.