Percent error question?

I really need help with this 2 problems can you work it out and explain to me how to get the answers? Thanks 1. A student determines the density of an unknown metal to be 5.2g/ml. The actual value of the density of the metal is 4.8 g/ml. State the formula for percent error. Calculate the percent error. The... show more I really need help with this 2 problems can you work it out and explain to me how to get the answers? Thanks

1. A student determines the density of an unknown metal to be 5.2g/ml. The actual value of the density of the metal is 4.8 g/ml. State the formula for percent error. Calculate the percent error.

The second question is not a percent error question
2. How would you prepare 500 ml of 3 M HCl?
for this one the only thing I know is that 3 M HCl = 3 mol/L HCl
2 answers 2