A quality control team plots sample means on an -chart where individual part weights have mean and standard deviation . For samples of size , what is the upper control limit ()?

Answer and explanation

Correct answer: C.

  1. Step 1: Calculate the standard error of the mean: . The upper control limit is . **Answer: . Why not the others:** uses without dividing by (), uses 4 standard errors, and adds only one standard error.

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