M.G. Krein arrives at the train station each day at the same time on his way home from work. His wife arrives at the train station just in time to meet him and drive him home.

One day he gets off work early and arrives at the train station one hour earlier than usual. He decides to walk home. His wife meets him on the way, and he arrives home 10 minutes earlier than usual. For how long did he walk?

Send me an e-mail linded@nsuok.edu and I'll tell you if you are right.