Question

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

Answer 1

In a day, there are 24 hours. The fractional part of a day you spend sleeping is the ratio of the number of hours you sleep to the total number of hours in a day. This is shown below,
                                        r = 8 hours / 24 hours = 1/3
Thus, you sleep for 1/3 of your day. 

Answer 2

About 24 hours per 1 day
8/24=1/3