The variable z is directly proportional to x, and inversely proportional to y. when x is 15 and y is 9, z has the value 5. what is the value of z when x = 23, and y = 14 round to at least the thousandths place if needed.

Because Z is directly proportional to X and inversely proportional to Y, therefore

where k = constant.

When X = 15 and Y = 9, Z = 5. Therefore
k(15/9) = 5
k = 5*(9/15) = 3
That is,


When X = 23, and Y = 14, obtain
Z = (3*23)/14 = 4.9286

 Z = 4.929 (nearest thousandth)