On March 1, Imhoff Co. began construction of a small building. Payments of $400,000 were made monthly for four months beginning March 1. The building was completed and ready for occupancy on June 1. In determining the amount of interest cost to be capitalized, the weighted-average accumulated expenditures are? How would I calculate this?

You probably will answer that $400,000 * ((3/12)+(2/12)+1/12))=200,000

But Why is that weighted as 3/12, 2/12 and 1/12 if the project was outstanding just for 3 months started from March 1 and ended in June 1. Shouldn't it be 3/3, 2/3, 1/3? Why?