Lorin management services has an unfunded postretirement benefit plan. on december 31, 2018, the following data were available concerning changes in the plan's accumulated postretirement benefit obligation with respect to one of lorin's employees: apbo at the beginning of 2018 $ 16,364 interest cost: ($16,364 × 10%) 1,636 service cost: ($44,000 × 1/22) 2,000 portion of epbo attributed to 2018 apbo at the end of 2018 $ 20,000 required: 1. over how many years is the expected postretirement benefit obligation being expensed (attribution period)? 2. what is the expected postretirement benefit obligation at the end of 2018? 3. when was the employee hired by lorin? 4. what is the expected postretirement benefit obligation at the beginning of 2018?