Tony (SA-I) and Jack (junior) were tasked by their audit manager to conduct an audit of the accounts receivable (A/R) and accounts payable (A/P) accounts. During the first two days of the audit, Jack, under Tony's supervision, efficiently completed the A/R audit work, and then moved on to the A/P audit. To Tony's delight, Jack completed all the A/P audit work in just 6 hours and then sat idle for further instructions. Jack explained to Tony how he performed the A/P audit. First, he classified the A/P accounts into three categories: A, B, and C. Category A accounts were those with balances over $50,000, and Jack's confirmation procedures covered 100% of those accounts. He obtained the A/P balance for each account from the A/P sub-ledgers and then requested confirmation from the vendor of the audit client. Category B accounts were those accounts with balances between $3,000 and $50,000, and Jack's confirmation procedures covered 20% of those accounts. For the remaining A/P accounts with balances under $3,000, they all belonged to Category C, and Jack only took a 5% sample (in terms of the number of sub-ledger accounts) and sent confirmations. As a star graduate of Catalina State University, Short Colina (CSUSC), Jack proudly reminded Tony that he still remembered the concept of materiality from Prof. Zheng's class. Jack's approach effectively covered 94% of the total dollar value of A/P accounts, impressing Tony again, who is also a CSUSC alumnus.

Tony was pleased to have such an excellent colleague.

Please answer if his audit process was correct.