to great lengths to improve their times, looking into factors such as the equipment they use and the coaches they hire. Listed in the table below are the personal best times for the 100 metre sprint for 27 sprinters that are in training. The 27 sprinters were chosen as follows: For each of three shoe brands (the Fast, the Quick and the Speedy brand), 9 sprinters who used that particular brand were randomly selected. The sample variances of the times for each shoe brand are also listed in the table.