  We investigate the survival rate of an initial momentum anisotropy
(${v}_2^{ini}$), not spatial anisotropy, to the final state in a multi-phase
transport (AMPT) model in Au+Au collisions at $\sqrt{s_{NN}}$=200~GeV. It is
found that both the final-state parton and charged hadron $v_2$ show a linear
dependence versus $v_2^{ini}\{\rm PP\}$ with respect to the participant plane
(PP). It is found that the slope of this linear dependence (referred to as the
survive rate) increases with transverse momentum ($p_T$), reaching~$\sim$100\%
at $p_T$$\sim$2.5 GeV/c for both parton and charged hadron. The survival rate
decreases with collision centrality and energy, indicating decreasing survival
rate with increasing interactions. It is further found that a $v_2^{ini}\{\rm
Rnd\}$ with respect to a random direction does not survive in $v_2\{\rm PP\}$
but in the two-particle cumulant $v_2\{2\}$. The dependence of $v_2\{2\}$ on
$v_2^{ini}\{\rm Rnd\}$ is quadratic rather than linear.
