Minimum is the time for the quickest packet to "get there and back".
Maximum is the time for the slowest packet to "get there and back".
I was telling you that you need to perform these tasks over a period of time. Just because your RTT is 79ms (average) now, does not mean that it will usually be 79ms. Doing one measurement and applying it as a rule is pointless and inaccurate. Perform these tests over various periods (including when things are busy) and then you'd have a good idea of what your RTT is.
