Instruction 18-15
the Manufacturer of Canned Food Constructed Control Charts

Instruction 18-15
The manufacturer of canned food constructed control charts and analysed several quality characteristics. One characteristic of interest is the weight of the filled cans. The lower specification limit for weight is 2.95 kg. The table below provides the range and mean of the weights of five cans tested every 15 minutes during a day's production.
$$\begin{array} { | l | l | l | l | l | l | } \hline \text { Number } & \text { XBar } & \text { Range } & \text { Number } & \text { XBar } & \text { Range } \\\hline 1 & 3.05072 & 0.0215 & 16 & 3.04646 & 0.073 \\\hline 2 & 3.01228 & 0.087 & 17 & 3.03868 & 0.0696 \\\hline 3 & 3.03558 & 0.0851 & 18 & 3.03338 & 0.0329 \\\hline 4 & 3.01014 & 0.0674 & 19 & 3.03322 & 0.0455 \\\hline 5 & 3.00858 & 0.0983 & 20 & 3.05078 & 0.0215 \\\hline 6 & 3.02704 & 0.0527 & 21 & 3.04808 & 0.0396 \\\hline 7 & 3.04268 & 0.0508 & 22 & 3.05348 & 0.0581 \\\hline 8 & 3.01052 & 0.0791 & 23 & 3.05516 & 0.0682 \\\hline 9 & 3.03464 & 0.0663 & 24 & 3.03426 & 0.0325 \\\hline 10 & 3.02034 & 0.0538 & 25 & 3.0516 & 0.0641 \\\hline 11 & 3.03764 & 0.0584 & 26 & 3.05562 & 0.0809 \\\hline 12 & 3.0409 & 0.0434 & 27 & 3.04402 & 0.0374 \\\hline 13 & 3.0519 & 0.0762 & 28 & 3.06458 & 0.0284 \\\hline 14 & 3.03994 & 0.0833 & 29 & 3.0544 & 0.0738 \\\hline 15 & 3.03788 & 0.0601 & & & \\\hline\end{array}$$
-Referring to Instruction 18-16,the chart is to be used for the time required to register.One way to obtain the control limits is to take the grand mean and add and subtract the product of A₂ times the average of the sample ranges.For this data set,the value of A₂ is _______.