For each question, be sure to show your work, starting with the formula you used, followed by the values substituted, etc. Be sure your final answer includes the units.

This problem begins to explore propagation delay and transmission delay, two central concepts in data networking. Consider two hosts, A and B, connected by a single link at the rate R bps. Suppose that the two hosts are separated by m meters, and suppose the propagation speed along the link is s meters/sec. Host A is to send a packet of size L bits to Host B. The propagation delay, dprop, is expressed in terms of m and s. The transmission time of the packet, dtrans, is expressed in terms of L and R. Ignoring the processing and queuing delays, obtain an expression for the end-to-end delay.

1. Suppose s = 2.5 * 108 meters per second, L = 120 bits, and R = 56 kbps. Find the distance m so that dprop equals dtrans.