Question

The variable z is directly proportional to x, and inversely proportional to y. When x is 20 and y is 6, z has the value 66.666666666667. What is the value of z when x= 25, and y= 12

Answer 1

41.667 to the nearest thousandth.

Explanation:

z = kx/y where k is the constant of proportionality.

Inserting the given values:

66.666666666667 = k*20/6

20k = 6*66.666666666667

k = 6*66.666666666667 / 20

= 20

So the equation of variation is z = 20x /y

When x = 25 and y = 12:

z = 20*25/12

= 41.666666666667.