A local children's boutique specializes in formal wear for young girls. It has recently hired a new seamstress. To assure the dresses have standard sizes, twenty samples of each 12 dresses that were labeled 3T were sampled. The average length from shoulder to hemline measured 21 inches with a range of 0.5 inches. A sample has just been taken with the following lengths: 21.25, 22.0, 21.5, 20.75, 21.25, 21.35, 21.35, 21.35, 21.35, 21.35, 21.35, and 21.35. Is the new seamstress performing at an acceptable quality level?
The solution illustrates the use of control charts to verify the process in control.