Three numbers are in the ratio of 2 : 3 : 5. Given that the product of the extremes is 90, find the difference between the largest and the smallest of them

$\begin{array}{l}2x\times 5x=90\\ x^2=9\\ 2x\times 5x=90\\ x^2=9\\ x=3\end{array}$

1^st number $=2x=2\times 3=6$

2^nd number $=3x=3\times 3=9$

3^rd number $=5x=5\times 3=15$

The difference between the largest number and the smallest number

$=15-6=9$