Question

Find the mean proportional between: $0.9$ and $2.5$

Answer 1

The mean proportional of $0.9$ and $2.5$ is $\sqrt{0.9\times 2.5}$

$=\sqrt{\frac{9\times 25}{10\times 10}}=\sqrt{\frac{225}{100}}=\frac{15}{10}=1.5$.