If a silver dollar contains 91.0% silver by mass, how many kilograms of silver can be extracted from 6.34 kg of silver dollars?

5.7 kg of silver

Explanation:

This data 91.0% silver by mass means, that in 100 g of silver dollar, 91 g are silver.

Let's work with a rule of three. Previously, convert g to kg (/1000)

100 g = 0.1kg

If in 0.1 kg we have 91 grams of Ag

In 6.34kg we would have (91. 6.34) / 0.1 = 5769.4 grams of Ag

This can be converted to kg.

5769.4 g = 5.7 kg