An electronics device emits a timing signal that should be as close to 300 milliseconds as possible (the historical process standard deviation is 5 milliseconds). A hypothesis test is setup so that, periodically, 40 devices are inspected to determine if the process average differs from the 300 millisecond target.
Forty devices are inspected with the following results (time in ms):
301.9 301.1 306.5 307.1 308.3
299.4 298.9 298.3 294.7 293.0
303.0 293.9 294.9 302.6 304.5
297.5 304.3 293.2 303.9 301.8
293.7 301.1 308.1 293.9 307.2
307.6 302.8 304.9 303.0 302.6
298.6 293.2 306.4 304.5 296.5
305.9 301.1 303.8 307.5 304.2
A run chart is developed that confirms process stability. The level of significance is chosen to be 0.01.
a. Is there evidence to suggest that the process average differs from the target value?
b. What is the p-value in this situation?