Pangli Co ( Mar/ June 2017)

Dear sir,
I have a doubt with this question.
In the question it is mentioned that
All sales are on credit and they are expected to be $3·5m for 20X6. Monthly sales are as follows:
November 20X6 (actual) $270,875
December 20X6 (forecast) $300,000
January 20X7 (forecast) $350,000

Pangli Co has a gross profit margin of 40%. Although Pangli Co offers 30 days credit, only 60% of customers pay in the month following purchase, while the remaining customers take an additional month of credit.

Yet when the receivables for Jan 20X7 are calculated, the receivable of $350,000 are included. Why is that so?

Thanks!