A quadratic function?
Like in the form y = ax^2 +bx +c ?
That will pass the point (50.8,120)
Tweak the "a" so that the graph will pass through (50.8,120)?
Okay, nothing will stop you from using the quadratic y = ax^2.
You can forget about the bx and c....since they are not specifically called for.
y = ax^2
120 = a(50.8)^2
a = 120 /(50.8)^2
a = 0.0465
That is it.