The mean score is 60 out of 100 and the standard deviation (in other words, the variation in the scores) is 15 marks (see our statistical guides, Measures of Central Tendency and Standard Deviation, for more information about the mean and standard deviation).
What Are the Six Different Types of Swimming Strokes? Swimming provides all-around, low-impact body conditioning as well as exciting competition. Competitive swim meets allow only four strokes -- butterfly, backstroke, breaststroke and the crawl. Two other strokes -- elementary backstroke and sidestroke -- contribute to swimming longer distances, as different sets of muscles are used. The fastest stroke for most swimmers is the front crawl.
World record progression 50 metres backstroke. This is a listing of the history of the World Record for the 50 backstroke swimming event. Swimming World Records are maintained by FINA, the international sports federation which oversees the sport. World Records are recognized only in meter-courses: long course (50m) and short course (25m).