That above 4:05 one is impossible without hooks.
First barracks comes up at 2:00. That gives 125 sec for production from one barracks. 125/8 = 15 marines
Second comes up at 2:30. that gives 95 sec for production from one barracks. 95/8 = 11 marines.
Total: 26 marines, assuming you have zero delay on resources and creation of buildings/units. Close, but looking at more like 4:20-4:30 under perfect circumstances, probably 4:45-5:00 worst case.
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