Question

Assume that y varies inversely with x. If y = 3.75 when x = 9, what is x when y = 6.75?

Answer 1

`x=5`

Explanation:

If `y` varies inversely as `x`, this means `yprop1/x` i.e. `y=k×1/x`, where `k` is a constant.

Hence, `xy=k`

Now as `y=3.75`, when `x=9`,

`k=9×3.75=33.75`

And so if `y=6.75`,

`x=k/y=33.75/6.75`

= `3375/675`

= `(3×3×3×5×5×5)/(3×3×3×5×5)`

= `5`