Select all the situations that can be represented by an exponential function.
1. Jim deposits $1,000 in an account that doubles in value every 7 years.
2. Brian deposits $30 in a savings account. Then he deposits $2 each month for the next 9 months.
3. Leon runs a mile in 8 minutes. Then he runs a mile each day for the next 4 days, reducing his time by 1.5% each day.
4. Cynthia runs a mile in 9 minutes. Then she runs a mile each day for the next 4 days, reducing her time by 6 seconds each day.
5. Marie deposits $30 in a savings account. Then she makes a deposit each month for the next 9 months, putting in $2 more with each deposit. Please answer with an actual question as fast as you can.