Jane is charged a finance fee of $43.20 for her October balance.
October Balance: $400
December 6: Jane paid off $100, leaving a balance of $300.
December 14: Jane paid off the remaining $300.
Now, calculate the daily finance fee:
Daily Interest Rate: 1.8% or 0.018
Daily Fee = Balance * Daily Interest Rate
Daily Fee = $300 * 0.018 = $5.40
For 8 days (from December 6 to December 14):
Total Fee = Daily Fee * Number of Days
Total Fee = $5.40 * 8 = $43.20
Therefore, Jane is charged a finance fee of $43.20 for her October balance.