Question

Check whether the following are proportions are not.
25 : 10 :: 10 : 4
7 : 21 :: 4 : 12

Answer 1

Answer:

Your first proportion equation can be represented as

$\frac{25}{10} =\frac{10}{4}$   ( ratios can be represented as fractions and proportion symbol is as                                                   good as saying = )

When we cross multiply, we get $100=100$.

This implies that $25 : 10 :: 10 : 4$ is true.

The second proportion can be denoted as

$\frac{7}{21} = \frac{4}{12}$  ( ratios can be represented as fractions and proportion symbol is as                                                   good as saying = )

When we simplify, we get $\frac{1}{3} = \frac{1}{3}$.

This implies that $7 : 21 :: 4 : 12$ is true.