Suppose a 1 gbps point-to-point link is being set up between the earth and a new lunar colony. the distance from the moon to earth is approximately 385,000 km, and data travels over the link at the speed of light (3 x 10⁸ meters per
calculate the minimum rtt (two-way propagation time) for the link.(in other words, how long would it take to send a single bit to the moon and immediately bounce it right back to earth? )

The time required to send the data from Earth to Moon will be 1.28s while for a two way communication, to send it back to the earth, it will take double time i.e. RTT = 2.56s

Explanation:

Distance between Earth and Moon = 385,000 km = 3.85 x 10⁸m

Speed of data travel = speed of light ≈ 3 x 10⁸m/s

As, v=d/t

t=d/v

t=1.28s

RTT = Double of single way time taken = 2x1.28

RTT=2.56s

distance = 150m

displ = root (50 ^2 + 100^2)

root(2500+10000)

root 125000