Practical Mathematics K9Five remote research stations need to share their research data with all the other stations. Sadly, due to cost cutting at the design phase, the high bandwidth bi-directional data links all route through a central hub, so only two stations can share data at a time. The data sharing time is independent of the amount of data shared, but the switching time is huge. In total each transfer takes 1 minute.

What is the minimum amount of time required to fully share the data?