What fractional part of a day do you spend sleeping if you sleep 8 hours per day?

Well a day is 24 hours, and if you sleep 8 hours, you sleep 8/24 hours (which is 8/24 of a day.)

If you wanted to put it in simplest form (which is always good practice), you can divide the numerator and denominator by 8 so you get 1/3 of a day.

Hope I helped, and let me know if you have any questions :)