A direct current of 3.0 amp (efficiency 75%) was passed through 400 ml 0.2 M Fe2(SO4)3 solution for a period of 60 min. The resulting solution in cathode chamber was analysed by titrating against acidic KMnO4 solution 20 ml of KMnO4 required to reach the end point. Determine the molarity of KMnO4 solution.