Five college friends went on a tour of haunted houses in Savannah, Georgia. The tour lasted for nearly 4 hours. At the end of the tour each of the friends gave the tour guide a tip. How much tip did the tour guide get in total from the college friends?

Some professions that provide you with personalized service don't pay well and so they expect a tip - waiters and waitresses, cab drivers, tour guides, hotel bell hops (yes they do still exist in many places), hotel maids, valet attendants (they park your car for you), movers and barbers and hair dressers.  
Often, tips are based on percentages.