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7-47.
  1. At the Bright Idea Lighting Company ten flashlights are sampled each hour to determine whether the manufacturing process is in control. The UCL is 0.10 defective, and the LCL is 0.05 defective. Homework Help ✎

    1. Create a process control chart for the following hours.

      Hour

      1

      2

      3

      4

      5

      6

      7

      8

      9

      10

      11

      12

      13

      proportion
      defective

      0.06

      0.08

      0.09

      0.06

      0.05

      0.08

      0.08

      0.07

      0.11

      0.10

      0.05

      0.07

      0.04

      Hour

      14

      15

      16

      17

      18

      19

      20

      21

      22

      23

      24

      25

      proportion
      defective

      0.08

      0.08

      0.09

      0.08

      0.09

      0.09

      0.08

      0.09

      0.10

      0.06

      0.05

      0.05

      checksum 1.88

    2. As a quality control engineer for Bright Idea, what do you report about the process control?

Place the 'hours' on the x-axis and the 'proportion defective' on the y-axis. Scale the y-axis from 0.05 to 0.10.

Draw a centerline at y = 0.075 on your graph.
Comment on how close/far the points are relative to the centerline.
What about several points in a row staying above/below the centerline?