HELLO NAMAN,
there is one simple way to solve this question and i will tell you
you assume that the volume of water = 1litre ==>1000gms
moles of H2O = 1000/18
= 55.55
and mole fraction = 0.04
moles of ethanol = mole fraction X total moles
= 0.04 X 55.55
= 2.2
so molarity = 2.2/1litre
= 2.2M
THANK YOU