Answer: yes
Step-by-step explanation: when we’re asked to determine whether two ratios form a proportion, what we’re really being asked to do is determine whether the two ratios are equal because if the ratios are equal, we know they form a proportion.
So in this problem, we need to determine whether 3/9 = 4/12.
The easiest way to determine whether 3/9 = 4/12 is to use cross-products.
If the cross-products are equal, then the ratios are equal.
The cross-products for these two ratios are (3)(12) and (9)(4).
Are these products equal?
(3)(12) is 36 and (9)(4) is 36.
Since 36 = 36, we can see that the cross-products
are equal which means that the ratios are equal.
Since the ratios are equal, they do form a proportion.