smc

If twenty percent of the objects in the urn are beads, then the other $80$% of the objects must be coins. Since $40$% of the coins are silver, then $60$% of the coins must be gold. Therefore, $60$% of $80$% of the objects in the urn are gold coins. Since $.6\times .8=.48$, 48 percent of the objects in the urn must be gold coins. Thus the answer is $\boxed{48\%}$.