Density= mass/volume
mass of water = density of water * volume of water= 1000* 1.5= 1500 kg
mass of alcohol= density of alcohol * volume of alcohol= 800* 0.5= 400 kg
Mass of the mixture= 1500 kg+ 400 kg = 1900 kg
Volume of the mixture= 2m^3
Density of the mixture= Mass of mixture/ volume of mixture= 1900 kg / 2m^3 = 950 kg /m^3