Final answer:
The constant of proportionality for the points (8, 12) and (3, 4.5) which are in a proportional relationship is 1.5. This is found by dividing the y-coordinate by the x-coordinate for each point.
Step-by-step explanation:
If the points (8, 12) and (3, 4.5) belong to a proportional relationship, we can find the constant of proportionality by dividing the y-coordinate by the x-coordinate for each point. The proportion should be the same for both points since they're part of the same proportional relationship.
For the first point (8, 12), the constant of proportionality (k) can be calculated as 12 ÷ 8 = 1.5. For the second point (3, 4.5), the constant of proportionality (k) can be calculated as 4.5 ÷ 3 = 1.5. Since both calculations give us the same constant of proportionality, we can conclude that the constant of proportionality (k) is indeed 1.5.