Final answer:
The constant of proportionality, k, can be found by setting up an equation and solving for k. In this case, k = 2.5.
Step-by-step explanation:
The constant of proportionality can be found by setting up an equation using the given information.
The equation is: 5 = k * 2
Now, to find the value of k, we can divide both sides of the equation by 2.
This gives us: k = 5/2 = 2.5
Therefore, the constant of proportionality is k = 2.5.