Over this period, the average gold-to-silver ratioSince 1687, the gold-to-silver ratio has ranged from 14.14 to 99.76 (see chart below). was 27.28 and today (March 8, 2012) the gold-to-silver ratio is 50.09.
If silver were to rise to bring the gold-to-silver ratio back to its long-term average, the silver price must rise to $61/oz. (Of course, gold (GLD) prices could also fall to lower the ratio. But let's assume gold is priced at fair value.)
If the ratio were to return to the pre-1900 average of 16.13, the silver price would have to rise to about $105/oz.