18. The data shown below give subgroup averages and moving averages of the values from Problem 17. The span of the moving averages is k = 8. When in control the subgroup averages are normally distributed with mean 50 and variance 5. What can you conclude?

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X 50.79806 46.21413 M 50.79806 48.50609 51.85793 49.62337 50.27771 49.78696 53.81512 50.59259 50.67635 50.60655 51.39083 50.71859 51.65246 50.83533 52.15607 51.00508 54.57523 52.05022 53.08497 52.2036 55.02968 52.79759 54.25338 52.85237 50.48405 52.82834 50.34928 52.69814 50.86896 52.6002 52.03695 52.58531 53.23255 52.41748 48.12588 51.79759 52.23154 51.44783