Final answer:
For every 1 cup of white paint, 3/7 cups of red paint are needed to maintain the same shade of pink. The constant of proportionality in this scenario is 3/7.
Step-by-step explanation:
To find out how many cups of red paint should be added to 1 cup of white paint to maintain the same shade of pink, we need to set up a ratio. The original mixture was 3 cups of red paint to 7 cups of white paint. This ratio must stay consistent for any amount of paint we mix.
We can write this as a proportion: 3/7 = x/1, where x is the amount of red paint needed for 1 cup of white paint. Solving this proportion by cross-multiplying gives us 3 = 7x, which simplifies to x = 3/7. Therefore, for every 1 cup of white paint, 3/7 cups of red paint are needed to achieve the same shade of pink.
The constant of proportionality is the value that relates the two quantities in a proportional relationship. Here, it is 3/7, which means for every 1 unit of white paint, 3/7 units of red paint are added.