An ad agency tracks the complaints, by week received, about the billboards in it

ID: 358968 • Letter: A

Question

An ad agency tracks the complaints, by week received, about the billboards in its city:

This exercise contains only parts a, b, and c.

a) The type of control chart that is best to monitor this process is _________.

b) Using z = 3, the control chart limits for this process are (assume that the historical complaints rate is unknown):

UCLc = ? complaints per week (round your response to two decimal places).

LCLc = ? complaints per week (round your response to two decimal places and if your answer isnegative, enter this value as 0).

c) According to the control limits, the process has been ______? (In/Out of Control).

Week # of Complaints 1 4 2 5 3 5 4 14 5 3 6 5

a) c-chart are best to use

b) c-bar = Number of complaints/Number of weeks = (4+5+5+14+3+5)/6 = 6

z = 3

UCL = c-bar + z*sqrt(c-bar) = 6 + 3*sqrt(6) = 13.35

LCL = c-bar - z*sqrt(c-bar) = 6 - 3*sqrt(6) = -1.35. So, 0

c) Out of control. As on week 4 complaints were above UCL

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