We report a measurement of the ratios of the decay rates of the
B^+, B^0 and B^0_s mesons into exclusive final states containing a J/psi
meson.  The final states were selected from 19.6 pb^-1 of ppbar collisions
recorded by the Collider Detector at Fermilab.  These data are interpreted to
determine the b quark fragmentation fractions f_u, f_d, and f_s.  We also
determine the branching fractions for the decay modes B^+ -> J/psi K^+, B^+ ->
J/psi K^*(892), B^0 -> J/psi K^0, B^0 -> J/psi K^*(892)^0 and B^0_s -> J/psi
phi(1020).  We discuss the implications of these measurements to B meson decay
models.