9.82 Breaststroke Swimmers How much training time does it take to become a world-class breaststroke swimmer? A survey published in The American Journal of Sports Medicine reported the number of metres per week swum by two groups of swimmers- those who competed only in breaststroke and those who competed in the individual medley (which includes breaststroke). The number of metres per week practicing the breaststroke swim was recorded and the summary statistics are shown below.

Is there sufficient evidence to indicate a difference in the average number of metres swum by these two groups of swimmers? Test using a = 0.01.

Breaststroke Individual Medley Sample size 130 80 Sample mean (m) 9017 5853 Sample standard deviation 7162 1961