If x is inversely proportional to y and y is directly proportional to z, then xz is :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Constant
‘x is inversely proportional to y’ means \(x=\displaystyle\frac{k}{y}\); ‘y is directly proportional to z’ means \(y=mz\), where \(k\) and \(m\) are constants.
Putting \(y=mz\) into the first relation: \(\displaystyle x=\frac{k}{mz}\)
\(\displaystyle xz=\frac{k}{m}\), a fixed number
So x is inversely proportional to z as well, and the product xz is constant.