Answer
$[Ag]=3.15\;ppm\;Ag$
Work Step by Step
Given concentration of Ag:
$2.86\;g\;Ag\div1\;ton\;ore$
Convert a ton to grams:
$2.86\;g\;Ag\div907,183\;g\;ore$
Using a proportion:
$\frac{2.86\;g\;Ag}{907,183\;g\;ore} = \frac{x\;parts\;Ag}{1,000,000\;parts\;ore}$
$[Ag]=3.15\;ppm\;Ag$
