Edwards Industries has a defined benefit pension plan for their 240 employees. The company decided to amend the pension plan, resulting in an increase of $3,680,000 to the projected benefit obligation. Edwards estimates that 15% of the employees will leave the company by the end of the first year, 20% in the second year, 35% in the third year, and 30% in the fourth year. What is Edwards' cost per service-year if the company uses the years-of-service method? $6,279.86 $8,518.52 $3,833.33 $5,476.19.

Could you please do it step by step with the math calculations? thank you