[mass]

Solution A contains paracetamol (C8H9N02).

10ml of solution A was diluted to 200ml and 10ml of the resulting solution was diluted to 200ml (solution B). Analysis of solution B showed that the concentration of C8H9N02 WAS 0.00188%w/v.

Calculate %w/v of C8H9N02 in solution A.

I know %w/v is 0.00188/100 but where do I go from there? Do I find a dilution factor.

[sjb]

I know %w/v is 0.00188/100 but where do I go from there? Do I find a dilution factor.

Yes. Consider how the concentration changes from solution A to B if the initial concentration was a generic x %w/v