Session p. 137

\(ExpectedVisits[ϵ_] := 
      1/ArithmeticGeometricMean[\@\(1 - 4 \((p\_EW + p\_NS)\)\^2\), \@\(1 - 4 \((p\_EW - p\_NS)\)\^2\)] /. {p\_EW -> \ \@\(\((1\/4 + ϵ)\) \((1\/4 - ϵ)\)\), 
          p\_NS -> \ 
            1\/4}; \({Precision == #, \(ϵ\_*\) == \ \((ϵ /. FindRoot[
                    ExpectedVisits[ϵ] == 2, {ϵ, 0.06, 
                      0.07}, WorkingPrecision -> #, 
                    AccuracyGoal -> #])\)} &\) /@ {13, MachinePrecision, 
          19, 22, 25} // TableForm\)