In order to determine the water content of a wet sand, a sample weighing 4 N was put in a pyknometer. Water was then poured to fill it and the weight of the pyknometer and its contents was found to be 22.5 N. The weight of pyknometer with water alone was 20.3 N. The grain specific gravity of the sand was known to be 2.67. Determine the water content of the sand sample.