Using R chart formulae, we get the value of upper control limit (UCL) is 12.57 and lower control limit (LCL) is zero.
As the name implies, R chart uses the subgroup range, R, to chart the
process variability (frequently over time), and to chart the
process location (frequently over time). Stable processes yield subgroups that enabling us to construct an
R chart. Estimates of the standard
errors of R is based on the average subgroup range R . The average of the R values is called R bar and it is computed by taking the simple arithmetic average of the R values:
R bar = ∑R/k
where k is the number of subgroups in Range R
Using this we construct the upper control limit and the lower control limit, we have
UCL(R) = R bar (d₄ ) ---(1)
LCL(R) = R bar (d₃) ----(2)
where, R bar --> average range
d₃ and d₄ are tabulated as subgroup function
Now, we have provided informations are
R chart has average range (R bar ) = 6.5
Average mean ( x bar ) = 150,d₃= 0,d₄=2.11
We compute the value of Upper Control limit (UCL) and lower control limit ( LCL)
so, using (1) and (2)
UCL(R) = 6.5 × 2.11 = 13.715
LCL (R) = 6.5 × 0 = 0
Hence, the Upper control limit is 13.75 and lower control limit is 0.
To learn more about R chart , refer:
#SPJ4