A certain auto repair shop services a particular make of car in the downtown region of a particular city. Three years ago, 4% of all repairs at this shop were not successful --- the mechanics were not able to restore the car to a drivable state. This year, only 2% of all repairs were not successful. Clearly, the mechanics training course, given over a year ago, has considerably increased the skill of mechanics at this particular shop
that fewer cars are beyond their ability to repair.
The manufacturer of this particular make of car recalled a few models due to defects that potentially jeopardized the engine.