Using the data accumulated in 2002–2004 with the D0 detector in proton-antiproton collisions at the Fermilab Tevatron collider with a center-of-mass energy of 1.96 TeV, the branching fractions of the decays B(2420)µ+µX and B(2460)µ+µX and their ratio have been measured: (B)×(Bµ+µX)×(D*-+)=[0.087±0.007(stat)±0.014(syst)]%; (B)×(Bµ+µX)×(D*-+)=[0.035±0.007(stat)±0.008(syst)]% and [(Bµ+µX)×(D*-+)]/[(Bµ+µX)×(D*-+)]=0.39±0.09(stat)±0.12(syst), where the charge conjugated states are always implied.