Jansen Company sells a product for $400 per unit, which includes a 30day warranty against product defects. Experience indicates that four percent of the units sold will prove defective, requiring an average repair cost of $50 per unit. During the first month of business, product sales were $320,000, and 20 of the units sold were found to be defective and repaired during the month. What is the accrued liability for product warranties at monthend?