Question

If y varies jointly as x and z when x = 5, y = 80, and z = 8. what is y when x = 16 and z = 2?

Answer 1

We are given that y varies jointly as x and z

Mathematically,

$y=kxz$

Where k is the constant of proportionality.

When x = 5, y = 80, and z = 8

$\begin{gathered} y=kxz \\ 80=k\cdot5\cdot8 \\ k=\frac{80}{5\cdot8} \\ k=2 \end{gathered}$

So, the relationship becomes

$y=2xz$

What is y when x = 16 and z = 2?

$\begin{gathered} y=2xz \\ y=2\cdot16\cdot2 \\ y=64 \end{gathered}$

Therefore, the value of y is 64