Browsing: service deposit

Q. From 1983 to 1985, I worked part time for the USDA. I was a student at the time, so when I graduated, I left for a job in the private sector, and my retirement deductions were paid back to me. I was later hired by the Department of the Army, where I have been ever since. I recently made a service deposit for my USDA time. I served with USDA for 25 months, but the part-time hours add up to 15 months full-time equivalent. Will this add 15 months or 25 months to my FERS pension?