According to the personnel department, the average commuting time for workers within a 50-kilometre radius of your company's head office is 32 minutes. You suspect that, because of development in the area and increased traffic, the average commuting time has increased. Suppose you know that if the personnel department's estimate was correct, sample means would be normally distributed, with a mean of 32 minutes and a standard deviation of 5 minutes. You take a random sample of 20 employees, and calculate a sample mean of 40 minutes. Does this provide evidence that commuting times have increased?
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