PNG  IHDRz&;[0PLTE@@@ftRNSS pHYsetEXtTitleInftyEditor MathImageytEXtAuthorAdministrator*'tEXtDescription $ \sigma=\sqrt{V(F_{n})} $ctEXtCopyrightInftyProject@$tEXtCreation Time r'rr'rr wIDATxݔm =YG֎?vfi<iui}D߯DzDv~n!FbڅO11,NF\`ҁq6ϰlnMMSG9[ΎnLZ-JϕGf|Zh8f":R[tkt[BߋMޡ)MYa=>7l!,QOOBXH<\⇧MV$n(BM~4_(v/K'=P>-{Q4h?۲p5v.o(#X[ne