The following is an abstract from the working papers of the Tests of Controls – Billing Function and Recording of Sales for the Year End: 31/12/2021

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Define the objectives: Examine duplicate sales invoices and related documents to determine if the system has functioned as intended and as described in the audit program.

Define the population precisely (including stratification, if any): POS invoices and credit sales invoices for the period 1/1/2021 to 31/12/2021. First invoice number =140672. Last POS number = 283294. First credit sales invoice number = 3600. Last credit sales invoice number = 6531.

Define the sampling unit, organization of population items, and random selection procedures: Sales invoice number, POS invoice numbers ,and credit recorded in the sales files sequentially; random sampling.

Description of Attributes	Planned Audit
	EPER	TER	ARO
Invoice copy has customer signature	0	3	10
For Bulk Sales: Bulk order from number is entered on invoice details	2	8	10
Bulk order form details match invoice details	0	4	10

Required

1. What is the initial sample size of each of the attributes?
2. Using the number of exceptions of each of the attributes given below, find the computed upper error rate (CUER) 
3. For each of the attributes (control), is it operating effectively throughout the period under audit? State Yes or No and explain why? 
4. What is your assessment of the control risk of the Billing Function and Recording of Sales for the Year End: 31/12/2021?