A commerce student who is about to graduate decided to survey various firms in Hali Valley to see which offered the best chance for early promotion and career advancement. In approaching 18 different high-tech firms, the student asked (among other things) how much time must elapse after the initial hiring before a good technician can receive a promotion. Suspecting that there might be differences depending on whether it was a small new firm, a medium-size firm, or a large international firm, the student grouped the data by size of the firm as follows:

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