Ok,we can calculate the constant of proportionality as the slope of a line
with this equation
[tex]m=\frac{y2-y1}{x2-x1}[/tex]where (x2,y2) is a point to the right compared to (x1, y1)
for this case I will choose the points (2,6.28) and (3,9.42)
where (3,9.42) is (x2,y2)
[tex]\begin{gathered} m=\frac{9.42-6.28}{3-2} \\ m=\frac{3.14}{1} \\ m=3.14 \end{gathered}[/tex]if we want a more exact number we can divide one number by another
[tex]\begin{gathered} \frac{6.28}{2}=3.14 \\ \frac{9.42}{3}=3.14 \\ \\ \frac{15.7}{5}=3.14 \end{gathered}[/tex]so the correct constant of proportionality is 3.14