From the proportional relationship, it is found that the constant of proportionality between the mass and the amount of stretch is of 2.0 centimeters per gram.
------------------------
The constant of proportionality is:
[tex]\frac{48 \text{cm}}{24 \text{g}} = \frac{16 \text{cm}}{8 \text{g}} = \frac{20 \text{cm}}{10 \text{g}} = 2 cm/g[/tex]
Thus, the constant is of 2.0 centimeters per gram.
A similar problem is given at https://brainly.com/question/24797041