# Question

A high-level voltage power supply should have a nominal output voltage of 350 V. A sample of four units is selected each day and tested for process-control purposes. The data shown in Table 6E.3 give the difference between the observed reading on each unit and the nominal voltage times ten; that is,

xi =(observed voltage on unit i–350)10

(a) Set up x and R charts on this process. Is the process in statistical control?

(b) If specifications are at 350 V 5 V, what can you say about process capability?

(c) Is here evidence to support the claim that voltage is normally distributed?

xi =(observed voltage on unit i–350)10

(a) Set up x and R charts on this process. Is the process in statistical control?

(b) If specifications are at 350 V 5 V, what can you say about process capability?

(c) Is here evidence to support the claim that voltage is normally distributed?

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