Assuming this is for an interview / assessment (which it must be given the timescales), I would suggest that it doesn't matter what approach you take. It is more important that you have an approach than which approach you actually adopt.
I think the previous poster is correct. I would:
1. Focus on the business objective
2. Stay high-level, diving into the data only where absolutely required
3. Accept it is okay not to finish. What you should be able to do by the end of the hour is:
3a. Provide a high-level overview of what the data is telling you (and how that relates to the business objectives -- the "so what?" answer)
3b. Describe how you would continue analysing the data if you had more time available.
Get 3a + 3b right and you'll sail through the assessment.