Final answer:
This involves calculating the amounts in two accounts with different interest rates, given the total interest earned. The account with 4% interest has $4000, and the account with 7% interest has $12000.
Step-by-step explanation:
The account earning 7% has 3 times as much money as the account earning 4%. Let's denote the amount in the account earning 4% interest as x. Therefore, the amount in the account earning 7% interest is 3x. The total interest earned from both accounts is calculated as follows: Interest from the 4% account: 0.04 * x, Interest from the 7% account: 0.07 * 3x. Adding these together gives us the total interest: 0.04x + 0.21x = $1000. Combining like terms, we get 0.25x = $1000. Dividing both sides by 0.25, we find x = $4000. Thus, the account earning 4% interest has $4000, and the account earning 7% interest, which is 3 times as much, has $12000.