Final answer:
The average daily balance is $23.33 and the finance charge for May is approximately $0.115.
Step-by-step explanation:
To find the average daily balance, we need to calculate the sum of the balances for each day and divide it by the number of days in the billing cycle. Assuming a 30-day billing cycle:
- From May 2 to May 19 (18 days), the balance is $100.
- On May 20, the balance increases to $300.
- From May 21 to May 31 (11 days), the balance is $300.
The sum of the balances is $100 + $300 + $300 = $700. The average daily balance is $700 / 30 = $23.33 (approx.).
To calculate the finance charge, we multiply the average daily balance by the annual percentage rate (APR) and divide it by the number of days in a year.
Finance charge = ($23.33 * 0.18) / 365 = $0.115 (approx.).