How much can my DVR record?

How many hours of HD video can my DVR strore? How about SD video?

I love my DVR.  I can record my shows and movies and watch them whenever I want.  I know that when I record HD programs my DVR fills up fast.  To account for that I often record shows in non-HD (SD format).  This has me wondering: can I use some basic info that my DVR is giving to me to determine how many hours of HD and/or SD programming that my DVR can record?  Check out the video to get started.
http://www.screenr.com/embed/u1is
In the video I delete a SD (non-HD) program.  Then I delete an HD program.  How can I use this video to help me better understand the HD and SD storage that my DVR can hold? If I only record HDTV programming on my DVR about how many hours of recording time will I have? If I only record SD (non-HD) programming on my DVR about how many hours of recording time will I have? How many hours of SD programming can I record for every hour of HD programming? What percent of DVR memory is equivalent to one hour of SD or HD recording time? Should I consider my calculations as an estimate or exact?  If an estimate, then how much HD and SD recording time might my DVR actually have?  What values make sense?  Also, as students find various combinations of HD and SD recording time consider having students use this Two Variable Sum Chart to organize their thinking.

The activity: DVR-capacity.pdf

For members we have Word docs and solutions.

DVR-capacity.docx         DVR-sum-chart.xlsx      DVR-capacity-solutions.pdf

Actual Recording Time (Picture)

Great opportunity for a discussion on why student answers might be different than the actual recording time!

CCSS: 6.RP, 6.EE, 7.RP, 7.EE, 8.EE.7, 8.EE.8, HSA.CED.A.1, HSA.CED.A.2

from Yummy Math http://www.yummymath.com/2015/how-much-can-my-dvr-record/