The branching ratios of negative pions and protons due to the weak dec
ays of C-12(Lambda) and B-11(Lambda) hypernuclei were measured. The ne
gative pionic decay rates (Gamma(pi-)), proton-induced nonmesonic deca
y rates (Gamma(p)), total nonmesonic decay rates (Gamma(nm), and ratio
s of the Lambda n-->nn process to the Lambda p-->pn process (Gamma(n)/
Gamma(p)) were derived from the present measurements combined with pre
vious studies on the mesonic pi(0) and total decay rates. The measured
Gamma(pi-) shows that Pauli blocking is less effective than expected
due to pion distortion. We found that Gamma(nm) is nearly equal to uni
ty in units of the free-space Lambda-decay width. The present results
also indicate that Gamma(n) is almost twice that of Gamma(p). This is
in disagreement with calculations based on meson-exchange models in wh
ich Gamma(n) is strongly suppressed.