How many ounces of pure gold are in an 18 karat gold chain that weighs 2.8 ounces?

18 karat gold contains 75% gold, and 25% other metals in the alloy. 75% of 2.8 ounces yields a gold content of 2.1 ounces. Multiplying. 75 times 2.8 will yield the correct result.

Pure gold is 24 Karat's so the ratio of purity 18 karat gold is:

(Number of Karats of Gold chain) / (Number of Karats of pure Gold)

this will give us:

18/24

=3/4

The weight of pure gold in 18 Karat Gold will be:

(ratio of purity) * (Total weight of chain)

=3/4*18

=13 1/2 ounces

=13.5 ounces.