Question

Z varies inversely with x and directly with y. When x=6, y= 2, z=5. What is the value of z when x=4 and y=9?

Answer 1

`z=33.25`

Explanation:

As `z` varies inversely with `x` and directly with `y`, we can say

`zpropy/x` or `z=kxxy/x`, where `k` is a constant.

Now as `z=5` when `x=6` and `y=2`, we have

`5=kxx2/6` or `k=5xx6/2=15` i.e. `z=15xxy/x`

Hence, when `x=4` snd `y=9`

`z=15xx9/4=135/4=33.25`