Do these ratios form a proportion?

16¢ : 6 centiliters

24¢ : 9 centiliters

Yes, these ratios form a proportion. To check if two ratios form a proportion, we compare the cross products. In this case, the cross products are:

(16¢)(9 centiliters) = 144¢ centiliters
(24¢)(6 centiliters) = 144¢ centiliters

Since the cross products are equal, these ratios form a proportion.