Well, "P-waves" aka transverse waves, have their velocity increase as the medium which they transmit through becomes denser. and since the outer core is denser than the molten layers above it.........
also, i'm assuming that you need this for h/w, so if a question comes up asking if the p-waves velocity increases while entering the solid inner core, it's a trick question, because transverse waves can only transmit through gas and liquid mediums
appologies if this really is a question about earthquakes and not just waves in general, because in that case, i'm making an ass of myself