This is a three-layer seismic problem. Table 2 contains first-arrival times that were measured in both the forward and reverse directions. Find the seismic velocities for each layer; then average them...

This is a three-layer seismic problem. Table 2 contains first-arrival times that were measured in both the forward and reverse directions. Find the seismic velocities for each layer; then average them and use the average values to find

₁
and

₂
as well as the critical angle between layer 1 and layer 2.