The mean proportional between 0.08 and 0.18 is?

The correct answer is Option (4) → 0.12

The mean proportional between two numbers \(a\) and \(b\) is the number \(x\) that makes the three numbers proportional, \(a:x=x:b\). In a proportion the product of the means equals the product of the extremes, so \(x^{2}=ab\) and \(x=\sqrt{ab}\), the geometric mean of the two numbers.

• Product of the two numbers: \(0.08\times0.18=0.0144\)

• Its square root is the mean proportional: \(\sqrt{0.0144}=0.12\), since \(0.12\times0.12=0.0144\)