87. A weighed portion of perhydrol is 3.00 g after dissolution and dilution to 500 cm3, for titration of 25.00 cm3 of this solution, 40.50 cm3 of KMnO4 solution with C (1 / 5KMnO4) = 0.1000 mol / dm3 is consumed. How many percent of H2O2 is in perhydrol?