An HP laser printer is advertised to print text documents at a speed of 18 ppm (pages per minute). The manufacturer tells you that the printing speed is actually a Normal random variable with a mean of 17.57 ppm and a standard deviation of 3 ppm. Suppose that you draw a random sample of 11 printers.

Part i) Suppose the number of printers drawn is quadrupled. How will the standard deviation of sample mean printing speed change?






Part ii) Suppose the number of printers drawn is quadrupled. How will the mean of the sample mean printing speed change?






Part iii) Consider the statement: 'The distribution of the mean printing speed of the sampled printers is Normal.'




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