Question

Z varies directly as x and y, z = 6 when x=2 and y = 6. Find the value of z when x = 3 and y = 8

Answer 1

12

Explanation:

This is a joint variation problem:

z varies directly as x and y

Interpreting this;

z ∝ xy

Therefore;

z = kxy

z = 6, x = 2, y = 6

Now find k,

6 = 2 x 6 x k

6 = 12k

k =
`(1)/(2)`

To find the value of z;

x = 3, y = 8

z =
`(1)/(2)` x 3 x 8 = 12