A post-tensioned beam shown in figure in above Q#3, in which pre-stressing tendon is draped in a parabolic shape

A post-tensioned beam shown in figure in above Q#3, in which pre-stressing tendon is draped in a parabolic shape. Assume the initial prestressing force Pi= R x 670 lb, Pe = R x 572 Ib, fc' = 6000 psi, ec = 13 in. and ee = 6 in. The service dead and live load moments are MD = R x 3170 in.-Ib & MSD + ML = R x 9675 in.-Ib. Determine the limiting envelope for tendon location such that the limiting concrete fiber stresses are at no time exceeded. Consider the midspan, quarter-span, and beam ends as the controlling sections.