Question

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.

Answer 1

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

`Z=k (X)/(Y)`
where k = constant.

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

`Z= (3X)/(Y)`

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

Answer: Z = 4.929 (nearest thousandth)