A certain ore is 20.9 % nickel by mass. How many kilograms of this ore would you need to dig up to have 90.0 g of nickel?

Question

A certain ore is % nickel by mass. How many kilograms of this ore would you need to dig up to have  g of nickel?

Answer 1

Let "T" represent the total amount of ore. Then 20.9% of T, or 0,209T, will equal 90g

0.209T = 90

T = 90/0.209

T = 430.622 g.

But there are 3 significant figures in the givens of this problem, so we need to round our answer to 3 sig figs so the total amount of ore is 431 g. The question asks for kilograms though, so we need to divide by 1000 to get kg. 431/1000 = 0.431 kg