A process that is considered to be in control measures an ingredient in ounces. Below are the last 10 samples (each of size n = 5) taken. The population process standard deviation, σ, is 1.36.
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Samples
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1
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2
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3
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4
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5
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6
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7
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8
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9
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10
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10
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9
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13
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10
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12
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10
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10
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13
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8
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10
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9
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9
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9
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10
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10
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10
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11
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10
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8
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12
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10
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11
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10
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11
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9
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8
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10
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8
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12
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9
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9
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11
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10
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10
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11
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12
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8
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10
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12
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8
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12
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10
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9
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10
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10
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9
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9
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8
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9
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12
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a) What is σx?
b) If z = 3, what are the control limits for the mean chart?
c) What are the control limits for the range chart?
d) Is the process in control?