Precious metals and gems are measured in troy weights in the English system:
24 grains = 1 pennyweight (exact)
20 pennyweight = 1 troy ounce (exact)
12 troy ounces = 1 troy pound (exact)
1 grain = 0.0648 gram
1 carat = 0.200 gram
b. What is the mass of a troy ounce of gold in grams and in carats?