During the fiscal year ended December 31, 2017, Swanson Corporation engaged in the following transactions involving notes payable:

Aug. 6 Borrowed $12,000 from Maple Grove Bank, signing a 45-day, 12%

note payable.

Sept. 16 Purchased office equipment from Seawald Equipment. The invoice amount was $18,000, and Seawald agreed to accept, as full payment a 10 percent, three-month note for the invoice amount.

Sept. 20 Paid Maple Grove Bank the note plus accrued interest.

Nov. 1 Borrowed $250,000 from Mike Swanson, a major corporate stockholder. The corporation issued Swanson a $250,000, 15 percent, 90-day note payable.

Dec. 1 Purchased merchandise inventory in the amount of $5,000 from Gathman Corporation. Gathman accepted a 90-day, 14 percent note as full settlement of the purchase. Swanson Corporation uses a perpetual inventory system.

Dec. 16 The $18,000 note payable to Seawald Equipment matures today. Swanson paid the accrued interest on this note and issued a new 30-day, 16 percent note payable in the amount of $18,000 to replace the note that matured.

a. Prepare journal entries to record each of the above transactions. Use a 360-day year in making the interest calculations.

b. Prepare the adjusting entry needed at December 31 to accrue interest.

c. Provide a possible explanation why the new 30-day note payable to Seawald Equipment pays 16 percent interest instead of the 10 percent rate charged on the September 16 note.