. Based on the balance sheet excerpt for Apple Inc. above , what percentage of its total accounts receivable in 2009 and 2008 does Apple estimate will be uncollectible? In general, how does the amount of allowance for doubtful accounts relate to bad debt expense? In general, what are some factors that could cause a company's allowance for doubtful accounts to decrease? . Based on the balance sheet excerpt for Apple Inc. above , what percentage of its total accounts receivable in 2009 and 2008 does Apple estimate will be uncollectible? In general, how does the amount of allowance for doubtful accounts relate to bad debt expense? In general, what are some factors that could cause a company's allowance for doubtful accounts to decrease