Solution
= Solution
P-wave <seismic impedance> is $Z_P=\rho V_P$. In layer order limestone, sandstone, salt,
$$
\boxed{(Z_{P1},Z_{P2},Z_{P3})=(5.50,4.00,4.00)\times10^6\ \mathrm{kg\,m^{-2}\,s^{-1}}}.
$$
The salt's larger P-wave <seismic velocity> is exactly offset by its smaller printed <density>, so the second interface has no P-wave <seismic impedance> contrast in this stipulated model.