Translation:Fifty percent of them do not believe.
il ... percento // la percentuale >> ... percent // percentage. I could write a lot about the reason for masculine and cinquanta. You would lose time trying to understand and that would be useless. It is quicker and easier to learn this rule: [number] percent = "il [number] percento" the number is the same number as used for counting. "un, due, tre, quattro, venti, cinquanta, novanta" IL CINQUANTA PERCENTO.