- #1

Arcany

- 3

- 0

## Homework Statement

Piece of quartz containing gold weights 102,5g and average density is 7,98g/cm

^{3}. Density of quartz is 2,65g/cm

^{3}. How much does gold weight?

## Homework Equations

ρ=m/V

avg.ρ= m

_{1}+m

_{2}/V

_{1}+V

_{2}

## The Attempt at a Solution

Using average density I find that volume of this piece is 12,84cm

^{3}. ρ=m/V ⇒ V=m/ρ V=102,5/7,98=12,84

Now using formula for calculating average density(avg.ρ= m

_{1}+m

_{2}/V

_{1}+V

_{2}) I get that 7,98=m

_{1}+m

_{2}/12,84. Now 102,5=m

_{1}+m

_{2}⇒m

_{1}=102,5-m

_{2}so I place this into the formula.

7,98=(102,5-m

_{2})+m

_{2}/12,84 but now -m

_{2}and +m

_{2}cancel each other off and I can't seem to find what to do now. Can you please help?