"Hoe laat ben je opgestaan?"
Translation:At what time did you get up?
I wouls phrase that as "what time did you get up at?" Rather than starting with "at", it sounds so formal. It marked that translation as wrong.
Ending the sentence with "at" sounds very unnatural to me. And that's not because of the so-called rule against ending a sentence with a preposition. It's just that in this use, the "at" is entirely unnecessary. It would be, "What time did you get up?" which, I believe, is accepted as correct.