Simple Interest Problems

1. What would 21% interest be on a $500 credit card bill?
 
 

2. You take out a student loan for $20,000. How much interest would you pay if the rate were 5% for the duration of the loan?
 
 

3. You receive dividends on a savings account that your grandmother started for you. You earn 4% interest. She deposited $600. What is the total amount of money that would be in your account after the interest was added?