Telephone inquiries of 100 IRS "customers" are monitored daily at random by Xiangling Hu. Incidents of incorrect information or other nonconformities (such as impoliteness to customers) are recorded.
The data for last week follow:

Day No. of Nonconformities
1 5
2 10
3 23
4 20
5 15

(a) Using 3 standard deviations, the c-chart for the nonconformities is (Round your response to two decimal places).
(b) According to the c-chart, there variation in the incidents of incorrect information given out by the IRS telephone operators.