Math Professors -- On average, how many hours per week do you think is required to gain tenure? I have a question particularly for the math professors here. I just finished my second year as a PhD student at a top30 University, passed all my qualifying exams, and I've begun working with an adviser in an area I'm excited about. Since the end of the Spring semester I've done a LOT of thinking, and I'm not sure academia is for me. The main issue is my perception of the time that will be required (in terms of hours per week) to get tenure. I have a wife and kids, and I just can't sacrifice the time spent with them, even if it means giving up something I love. I figure I could put in 40-45 hours a week, but then I need to be home. My first year of grad school, I put in 60-70 hours a week, and I certainly never want to go back to that. This last year, I've kept it between 40-50, and that seems about right for work/life balance.

So my question is this... am I correct in ruling Academia out for this reason? I had considering smaller colleges, but I'm looking to earn at least $60k and from what research I've done, I won't make that much.

My next question involves research outside Academia. Is there any place for research in combinatorics, asymptotics, probability, and analysis of algorithms outside of Academia, where the work-culture is a typical 40 hour workweek? I see a lot of research in other areas of mathematics that I'm not interested in (PDE's, Scientific/Engineering, Number Theory) -- but not really what I'm interested in.

So with all that, it seems to me that I'm not even sure why I would get a PhD anymore, other than it might open doors, but it's hard to stay motivated when there is no clear goal, or thing to work towards. My current thinking is just take some CS courses and learn some programming languages, get an internship next summer and perhaps leave with a masters after a year or so unless I can think of a very good reason to stay.

Any advice is appreciated!!
I've said this in another thread: if you are outstanding and efficient, you can do the work required in a 40-hour workweek.  

An electrical engineering professor I know got through graduate school at MIT working 9-5 days with a wife and three kids (all born during school), and he was a shoo-in for tenure (and received it).  But, when he was at work, he was at work--I never once saw him out of work-mode during the regular day, and he put us graduate students to shame with his work ethic.  His efficiency and focus puts him over the top.  I know I couldn't be that efficient every day, but he makes it a priority to do the best he can at his job (which he loves) and also for his family, and he's figured out how to do it within the confines of a typical working week.  Granted, he is also extremely smart, but I believe his efficiency is as much responsible for his success as his brains.