How many hours do you put in?

I have been teaching on-line education classes for Grand Canyon Univerity for over a year now and I love it.  I often hear interesting things from my students and the one I heard today was worth a blog post.  Here is the quote:
"...educated women spend on average 21.5 hours per week attending to the needs of their children..."
I feel like I spend 21 hours a day tending to the needs of my children (and husbands count too right?).  Even if my kids were in school 5 days a week (sniff sniff), I would still have them at home for about 5 or 6 waking hours each day and then the whole weekend which would be more than 21 hours a week right?
Anyone else have an opinon on this?  I would love to see your comments!