Instruction 18-10
a Supplier of Silicone Sheets for Producers of Computer

Instruction 18-10
A supplier of silicone sheets for producers of computer chips wants to evaluate her manufacturing process. She takes a sample size of five from each day's output and counts the number of blemishes on each silicone sheet. The results from 20 days of such evaluations are presented below. She also decides that the upper specification limit is 10 blemishes.
$\begin{array}{llllllll}\text{Day}&1&2&3&4&5&\text{Mean}&\text{Range}\\\hline1 & 8 & 10 & 14 & 6 & 5 & 8.6 & 9 \\2 & 8 & 13 & 6 & 6 & 10 & 8.6 & 7 \\3 & 10 & 12 & 7 & 7 & 9 & 9.0 & 5 \\4 & 5 & 9 & 12 & 7 & 10 & 8.6 & 7 \\5 & 8 & 3 & 8 & 9 & 10 & 7.6 & 7 \\6 & 9 & 7 & 9 & 6 & 9 & 8.0 & 3 \\7 & 10 & 10 & 5 & 7 & 6 & 7.6 & 5 \\8 & 10 & 9 & 10 & 6 & 5 & 8.0 & 5 \\9 & 6 & 10 & 6 & 9 & 9 & 8.0 & 4 \\10 & 6 & 9 & 8 & 6 & 8 & 7.4 & 3 \\11 & 8 & 5 & 6 & 10 & 10 & 7.8 & 5 \\12 & 6 & 4 & 7 & 7 & 12 & 7.2 & 8 \\13 & 7 & 5 & 7 & 6 & 9 & 6.8 & 4 \\14 & 5 & 8 & 8 & 7 & 6 & 6.8 & 3 \\15 & 7 & 12 & 10 & 6 & 10 & 9.0 & 6 \\16 & 7 & 11 & 4 & 7 & 8 & 7.4 & 7 \\17 & 8 & 4 & 5 & 4 & 7 & 5.6 & 4 \\18 & 11 & 4 & 11 & 11 & 10 & 9.4 & 7 \\19 & 6 & 10 & 6 & 10 & 10 & 8.4 & 4 \\20 & 6 & 12 & 12 & 6 & 8 & 8.8 & 6\end{array}$

-Referring to Instruction 18-10,an R chart is to be constructed for the number of blemishes.One way to create the lower control limit involves multiplying the mean of the sample ranges by D₃.For this data set,the value of D₃ is _______.