Answer
$19.37^{\circ}$
Work Step by Step
We can find the required angle as follows:
$a=gsin\theta$
We plug in the known values to obtain:
$3.25m/s^2=(9.8m/s^2)sin\theta$
$\implies \theta=sin^{-1}(\frac{3.25m/s^2}{9.8m/s^2})$
$\theta=19.37^{\circ}$