Question

Determine if the following are in proportion:
$30,40,40,55$

Answer 1

$30,40,40,55$ (to determine whether they are in proportion)

If $\frac{a}{b}=\frac{c}{d}$ (numbers are said to be in proportion)

$\frac{a}{b}=\frac{30}{40}=\frac{3}{4}$;

$\frac{c}{b}=\frac{40}{55}=\frac{8}{11}$

Since, $\frac{a}{b}\ne \frac{c}{d}$

(They are not in proportion).