Answer:
[tex]\huge\boxed{\sf 3\ hours\ 47\ minutes}[/tex]
Step-by-step explanation:
Fell asleep = 11:25 AM
Woke up = 3.12 PM
When we go from 11:25 AM to 12:25 PM, he slept for 1 hour.
From 12:25 PM to 1:25 PM, it will be 2 hours.
From 1:25 PM to 2:25 PM, it will be 3 hours.
From 2:25 PM to 3:00 PM, it will be 3 hours 35 minutes.
From 3:00 PM to 3:12 PM, it will be 3 hours 35 minutes + 12 minutes.
So,
He slept for 3 hours 47 minutes.
[tex]\rule[225]{225}{2}[/tex]