8:15 AM - 11:42 AM = 3 hours and 27 minutes.
1:12 PM - 4:00 PM = 2 hours and 48 minutes.
3 hours + 2 hours = 5 hours.
27 minutes + 48 minutes = 1 hour and 15 minutes.
5 hours + 1 hour and 15 minutes = 6 hours and 15 minutes.
Natalie worked a total of 6 hours and 15 minutes.