# Calculating monthly interest for bank account

## Question

Suppose you're given the following table showing the monthly change in a bank account for a business:

Table: cash_flows

month | net_account_change |
---|---|

1 | 5000 |

2 | -1000 |

3 | 12000 |

4 | 3000 |

5 | 3000 |

6 | 6000 |

7 | 500 |

8 | 3000 |

9 | 6000 |

10 | 2000 |

11 | -4000 |

12 | 2500 |

The bank account started at $0 and earns an annual interest rate of 3% on the total account balance, paid out monthly (0.25% / month). Given this information, along with the table above, write a SQL query to return the account interest paid out each month. For simplicity, you can assume the cumulative total account balance does not go negative.

You can view/query the data in an interactive SQL fiddle here.