In 2020, Dana Corporation began selling a new line of products that carry a two-year warranty against defects. Based upon past experience with other products, the estimated warranty costs related to dollar sales are as follows: First year of warranty Second year of warranty 2% 4% Sales and actual warranty expenditures for 2020 and 2021 are presented below: 2020 Sales 300,000 Actual warranty expenditures 10,000 What is the estimated warranty liability at the end of 2021? 2021 400,000 20,000