A company that manufactures health food snacks produces low sodium rice chips. To monitor the process for sodium levels, chips are selected periodically and the amount of sodium (mg) measured. For each of thirty samples consisting of 8 chips, the mean and range in sodium content is determined. The average of the means across all samples is 55 mg and the average range is 2.2 mg. The lower and upper control limits for the R chart are

Question

Quizplus · Accepted Answer

The correct choice is A) 0.299 and 4.101 mg. This is because control limits for an R chart are calculated using the average range (R-bar) and factors from a statistical table based on sample size. For a sample size of 8, the appropriate factors (D3 and D4) are used to calculate the lower and upper control limits as follows: LCL = D3(R-bar) and UCL = D4(R-bar). Given the average range of 2.2 mg, and knowing the factors for a sample size of 8 (D3 and D4 values), the calculated limits match those in option A.

A Company That Manufactures Health Food Snacks Produces Low Sodium