Portion in this question refers to either the fraction, or percentage.
The amount of time people are normally advised to sleep is 8hours.
An entire day consists of 24hours.
To find the portion of the day we are advised to sleep = 8hrs/24hrs
{hrs unit cancels out}
= 8/24
{Simplify fraction}
= 1/3 of a day
Hope this helps! :)
