Determine which set of ratios forms a proportion

Question

1:8, 2:18
5:10, 20:40
9:10, 45:40
1:16, 3:18

Answer 1

The set of ratios that form a proportion is 5:10, 20:40.

To check if the ratios form a proportion, you can cross multiply and see if the resulting products are equal.

5 * 40 = 200
10 * 20 = 200

Since the cross products are equal, the ratios 5:10 and 20:40 form a proportion.