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.
The following times are the world records for the 50 meter backstroke for men and women and in short course (25 meter) and long course (50 meter) pools. Men's 50m Backstroke: Long Course: 24.04 seconds by British swimmer Liam Tancock at the 2009 FINA World Aquatics Championships in Rome.