(a) Allegations that a child has committed a delinquent act must be proved beyond a reasonable doubt.
(b) If trial by jury is demanded, the jury shall decide issues of fact raised by the petition and return its verdict as to the truth of the allegations contained in the petition. A finding by the jury that the allegations are true is not deemed a conviction of guilt, but is a determination that judicial intervention is necessary for the best interest and welfare of the child and the public.