Here are the ones that I messed up or were unsure of. Wording is approximate. There is no mention of any other requirements for your net. Share level Q is open to interpretation. But it says clearly the client computers, so are you to assume that there is a server, if so then user level.
Problem is broadcast storms.
Now I've looked high and low to how to calculate the output of those modems and have come up with conflicting answers. If U simply add up the output it will fail to meet the required 1mbps. However others have said add it all up and multiply by 12.5, don't ask where this figure comes from as I have no idea. It is possible for a modem to have an output above its stated speed if there is some form of data compression involved. But the Q says nothing about this.