The correct interpretation of the constant of proportionality in the equation \( y = 7x \) is:
The constant of proportionality is 7. It takes the crew of workers 7 weeks to complete 1 road project.
In this context, the equation indicates that for every road project (represented by \( x \)), it takes 7 weeks (represented by \( y \)) to complete that project. Hence, if you have \( x \) number of road projects, the total time \( y \) in weeks needed to complete all of them is calculated by multiplying the number of projects by 7.