Answer:
P = $381.39 * ((1 - (1 + 0.01825)^-36) / 0.01825)
P = $12,685.29
Therefore, the unpaid balance immediately after the ninth payment would be:
$10,000.00 - $12,685.29 = -$2,685.29
Since the unpaid balance cannot be negative, this means that the entire loan would be paid off after the ninth payment. Therefore, the unpaid balance would be $0.00.