An evaluation of the books of blair supply

P3-16 An evaluation of the books of Blair Supply, which follows, gives the end-of-year accounts receivable balance, which is believed to consist of amounts originating in the months indicated. The company had annual sales of $2.4 million. The firm extends 30-day credit terms.
Month of origin       Accounts receivable
July                                   $ 3,875August                                 2,000September                         34,025October                              15,100November                           52,000December                         193,000Year-end accounts receivable $300,000
a. Use the year-end total to evaluate the firm’s collection system.
b. If 70% of the firm’s sales occur between July and December, would this information affect the validity of your conclusion in part a? Explain.