Two machines are used to manufacture a specific part. A sample is taken 55 pieces made by both devices and it is found that the pieces produced by the Machine A have an average length of 64 mm with a standard deviation of 5 mm, while those of machine B an average length of 62 mm with a deviation 3mm standard. Determine if there is a difference between the length of the parts manufactured by each machine, with a significance level of 4%.