Telephone inquiries of 100 IRS \"customers\" are monitored daily at random. Inci
ID: 358964 • Letter: T
Question
Telephone inquiries of 100 IRS "customers" are monitored daily at random. Incidents of incorrect information or other nonconformities (such as impoliteness to customers) are recorded. The data for last week follow:
a) UCLc= ? Noncomformities (round your response to two decimal places).
LCLc= ? Noncomformities (round your response to two decimal places)
b) According to c-chart, there ___________ (is significant/Not significant) variation in the incidents of incorrect information given out by the IRS telephone operators
Day # Of Noncomformities 1 2 2 6 3 18 4 9 5 8Explanation / Answer
Number of days = 5
Sum of nonconfirmities = 2+6+18+9+8 = 43
C-bar = Sum of nonconfirmities/number of days
= 43 / 5
= 8.6
a) using a 3 sigma control limit:
UCLc = C-bar + [3(sqrt of C-bar)]
= 8.6 + [3(sqrt of 8.6)]
= 8.6 + (3 x 2.93)
= 8.6 + 8.79
= 17.39
LCLc = C-bar - [3 (sqrt of C-bar)]
= 8.6 - [3(sqrt of 8.6)]
= 8.6 - (3 x 2.93)
= 8.6 - 8.79
= - 0.19
= 0 (If the value is negative it is taken as 0)
b) According to the c-chart there is significant variation in the incident of incorrect information given out, because the number of nonconfirmity for day 3 is beyond the upper control limit of 17.39.
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