If the weight of soil is 1.0 g, amount of potassium dichromate (1 N) is 10 ml, volume of ferrous ammonium sulphate (0.5 N) solution required for blank titration is 20.1 ml and volume of ferrous ammonium sulphate (0.5 N) solution required for soil sample titration is 17.4 ml, then the organic carbon content (%) in soil will be: