"Consider a 100 Mbps Ethernet link. In order to have an efficiency of 0.70, what should be the maximum distance between two nodes? Assume a frame length of 64 bytes (including the Ethernet header) that is preceded by a 64-bit preamble and that the signal propagation speed is 2 x 10^8 m/s."

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I don't even know how to begin; I feel like I'm not given enough information (though I'm sure that's not the case). :(

4. (6 points) Consider a 100 Mbps Ethernet link. In order to have an efficiency of 0.70, what should be the maximum distance between two nodes? Assume a frame length of 64 bytes (including the Ethernet header) that is preceded by a 64-bit preamble and that the signal propagation speed is 2 x 108 m/s