Molarity chemistry question?

Question

A solution is prepared by dissolving 15.0 g of NH3 in 250 g of water. The density of the resulting solution is 0.974 g/mL. The molarity of N in the solution is __________.

Answer 1

I do confirm Dr. A 's answer.

Answer 2

Moles NH3 = 15.0 g / 17.0307 g/mol =0.881

Total mass = 15.0 + 250 = 265 g

Volume solution = 265 g / 0.974 g/mL =272 mL => 0.272 L

M = 0.881 mol / 0.272 L =3.24