As stated above, the time to MAP is based on groundspeed, not indicated airspeed. If your groundspeed is not exactly on the chart, you interpolate. If you have a 70kt and 90kt groundspeed shown, and your groundspeed will be 80kt, then your time will be halfway between those for the 70 & 90 figures.
I'm not sure what you mean by "IFR Airport Minimum Requirments". Minima are published for approaches, not airports.