The solubility-product constant for barium permanganate, Ba(MnO4)2, is 2.5×10-10. Suppose that solid Ba(MnO4)2 is in equilibrium with a solution of KMnO4.
What concentration of KMnO4 is required to establish a concentration of 1.7×10-8M for the Ba2+ ion in solution?
Express your answer using two significant figures.