  Based on the factorization in perturbative QCD, a jet cross sections in
heavy-ion collisions can be expressed as a convolution of the jet cross section
in $p+p$ collisions and a jet energy loss distribution. Using this simple
expression and the Markov Chain Monte Carlo method, we carry out Bayesian
analyses of experimental data on jet spectra to extract energy loss
distributions for both single inclusive and $\gamma$-triggered jets in $Pb+Pb$
collisions with different centralities at two colliding energies at the Large
Hadron Collider. The average jet energy loss has a dependence on the initial
jet energy that is slightly stronger than a logarithmic form and decreases from
central to peripheral collisions. The extracted jet energy loss distributions
with a scaling behavior in $x=\Delta p_T /\langle \Delta p_T\rangle$ have a
large width. These are consistent with the linear Boltzmann transport model
simulations, in which the observed jet quenching is caused on the average by
only a few out-of-cone scatterings.
