A hypothetical KamLAND-type experiment detects v̅_e neutrinos at a distance of 300 m from a nuclear reactor and finds that the flux is (90 ± 10)% of that expected if there were no oscillations. Assuming a two-component model with maximal mixing (θ = 45⁰) and a mean neutrino energy of 2.5 MeV, estimate the squared mass difference of the electron anti neutrino and its oscillating partner.