Induced drag is, by definition:
$D_i =qS \cdot\frac{C²_L}{\pi AR e}$
where $AR$ is the aspect ratio, $e$ the Oswald coefficient and $q=½ \rho V²$.
From this equation you can infer all the information that you need. In your experiment the only thing that changes is speed, then the induced drag is going to increase proportionally to it squared. At least until effects due to Reynolds number don't change $C_l$ or the spanwise lift distribution changes modifying $e$; but this can be neglected as a first approximation.
Anyway this is a pure academical exercise: in reality lift doesn't assume random values but equals the weight of the aircraft (except during manoeuvres). Substituting therefore the weight $W$ and doing some simplifications, one gets:
$D_i = \frac{W²}{q \pi e b²}$
where $b$ is the wingspan. This time $q$ is by the denominator and therefore the induced drag reduces with the speed squared i.e. the opposite of before.
Btw, induced drag belongs to pressure drag.