Question

Check the following number is in proportion or not? $12,15,18$ and $20$

Answer 1

Check the numbers are in proportion or not:

Let and $20$ are in proportion.

So, $12:15::18:20$

$\Rightarrow \frac{12}{15}=\frac{18}{20}$

$\Rightarrow \frac{4}{5}\ne \frac{9}{10}$

Hence, $12,15,18$ and $20$ are not in proportion.