  ### Home > INT3 > Chapter 7 > Lesson 7.1.4 > Problem7-47

7-47.

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.

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 $1.88$

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

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

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?