Total distance = 8000 Km = $8\times 10^{6} m$
Propagation speed = $2\times 10^{8} s$
$\therefore$ Propagation delay = $\frac{8\times 10^{6}}{2\times 10^{8}} = 0.04 s$
Total data size = 100 bits
Data rate = 1Mbps = $10^{6}$ bps
$\therefore$ Transmission time = $\frac{1000}{10^{6}} = 0.001 s$
$\therefore$ Total transmission delay during data transfer phase = Propagation time + Transmission time = 0.04 + 0.001 = 0.041 s
Reference: https://www.youtube.com/watch?v=DFM3UD6ggyI (at 25:00)
