I have circled in green where I think the mistake is. The questions says 4 people leave the island after day 5, which I believe it means there would be 6 people on Day6 and Day7 (2 full days) because they mention there is 1 person joining them in Day8, therefore there would be 7 people from Day8. Am I understanding this incorrectly?
I think the question itself (not the solution video) is slightly different?