Sandhill Company is constructing a building. Construction began on February 1 and was completed on December 31. Expenditures were $1,968,000on March 1, $1,248,000on June 1, and $3,076,020on December 31.

Sandhill Company borrowed $1,145,430on March 1 on a5-year,13% note to help finance construction of the building. In addition, the company had outstanding all year a9%,5-year, $2,433,900note payable and an10%,4-year, $3,482,600note payable. Compute the weighted-average interest rate used for interest capitalization purposes.