An examination of leptons in Υ(4S) events tagged by reconstructed
B decays yields semileptonic branching fractions of b−=(10.1±1.8±1.4)% for charged and b0=(10.9±0.7±1.1)% for neutral B mesons.
This is the first measurement for charged B. Assuming equality of the charged
and neutral semileptonic widths, the ratio b−/b0=0.93±0.18±0.12 is
equivalent to the ratio of lifetimes. A postscript version is available through
World-Wide-Web in http://w4.lns.cornell.edu/public/CLNS/1994Comment: 9 pages (in REVTEX format) Preprint CLNS94-1286, CLEO 94-1