Indicate whether each of the following audit procedures is a test of controls, a substantive test, or a dual purpose test. Next, indicate the financial statement assertion most closely related to each audit procedure. a. Vouch recorded sales invoices to supporting shipping documents. b. Inspect recorded sales invoices for credit approval. c. Vouch recorded sales invoices prices to the approved price list. d. Send confirmations to all customers regarding accounts receivable. e. Recalculate the arithmetic accuracy of the recorded sales invoices. f. Compare the shipment date of record sales invoices with the invoice record date. g. Trace recorded sales invoices to posting in the general ledger control account and in the correct customer's account. h. Select a sample of shipping documents from the shipping shipping department file and trace shipments to recorded sales invoices. i. Scan recorded sales invoices and shipping documents for missing numbers in sequence. j. Vouch sales invoices and shipping documents. k. Evaluate the adequacy of the allowance for doubtful accounts.