value of time

One day a boy asked his busy father, "Dad, how much money do you earn in an hour?" The impatient dad answered, "I don't know, I guess I make about $50 an hour when I'm at work. Now don't bother me, I'm busy." After a couple of weeks of doing odd jobs around his neighborhood, the little boy approached his dad one evening and said, "Dad, here's $25. Can I buy 30 minutes of your time so we can play together?"