Concentration Help!!!!!

What is the concentration (w/w %) if 75.0 grams of magnesium nitrate are combined with 500.0 mL of water?

Correct sig. figues and please explain how you got your answer

C=n/V
Volume is in litres so V = 0.500
M=m/n
M = molar mass of Magnesiun Nitrate = 148.3
m = mass in grams = 75.0
n = number of moles
n=m/M
= 75.0/148.3
= 0.5057316251 mol
C = n/V
= 0.5057316251/0.500
= 1.01 (3sf) molL^-1