Signal reflection data extracted from GPR measurements at a certain location of a fIexiole pavement (Location A) is shown below, The thickness of the core extracted from the asphalt concrete (AC) layer of the flexible at Location A is 17cm. 14000 AC (4.266, 11400). 12000 10000 Pavement Data 8000 6000 4000 Base (7.162, 4556) 2000 Subgrade 9 1011 121314 1516 17 18 19 2021 -2000 0 4000 -6000 -8000 Time (ns) GPR data collected at another location (Location B) of the same pavement section indicated that the amplitude of the GPR signal reflection at the pavement surface is 12200, and the two-way travel time of GPR signal within the AC layer is 3 ns. Determine the thickness of AC layer at Location B. Amplitude