Question

The variable z is inversely proportional to x. When x is 16, z has the value 0.875. What is the value of z when x= 21?

Answer 1

For $z$ and $x$ to be inversely proportional, there must be some constant $k$ such that

$zx=k$

Given that $z=0.875$ when $x=16$, it follows that

$0.875\cdot16=k\implies k=14$

Then when $x=21$, we have

$21z=14\implies z=\dfrac{14}{21}=\approx0.667$