Ask any Chem. 101 student.

We should generally take not fully specified % concentrations as wt% ― where wt is often omitted or can be substituted by either wt., wt/wt, wt./wt., or m/m ― meaning: (mass of pure solute / mass of solution)·100%; even if this is not clearly stated.

The concentration of HNO3 aq. is 0.550 (g HNO3 / g solution)·100%. The density of that sol. is 1.339 g/cm3 (20 ºC) after (e.g.) Table 2-66 in: R.H. Perry, D.W. Green, J.O. Maloney (Eds.), "Perry's Chemical Engineers’ Handbook", 7th ed., McGraw-Hill, 1997. The density is usually also available from the commercial label, being that a commercial solution. The molecular mass of HNO3 is 63.012 g·mol−1. The molarity is: 0.550(g HNO3 / g aq. sol.)·1.339(g aq. sol. / cm3)·(1000 cm3/dm3)/(63.012 g HNO3/mol HNO3) = 11.69 M (approximate).

The concentration of the mentioned copper nitrate, Cu(NO3)2, aq. sol. is 1.000 (g Cu(NO3)2 / g solution)·100%. The relative density of that sol. is 1.007 (20 ºC / H2O at 4ºC) after Table 2-48, ibidem. The density of H2O at 4ºC is 1.000 g/cm3. The molecular mass of (anhydrous) Cu(NO3)2 is 187.56 g·mol−1. The molarity is: 1.00(g Cu(NO3)2 / g aq. sol.)·1.007(g aq. sol. / cm3)·(1000 cm3/dm3)/(187.56 g Cu(NO3)2/mol Cu(NO3)2) = 5.369 M.