Answer: Let's denote the amount of money Liza deposited at 2.5% interest as x dollars. According to the problem, she deposited twice as much, or 2x dollars, at 5.5% interest.
To calculate the interest income from each deposit, we can use the formula: Interest = Principal × Rate × Time.
For the deposit at 2.5% interest:
Interest_2.5% = x × 0.025.
For the deposit at 5.5% interest:
Interest_5.5% = 2x × 0.055.
According to the problem, the total annual interest income is $1620. So we can set up the following equation:
Interest_2.5% + Interest_5.5% = 1620.
Plugging in the expressions for the interest at each rate, we get:
x × 0.025 + 2x × 0.055 = 1620.
Simplifying the equation:
0.025x + 0.11x = 1620.
0.135x = 1620.
x = 1620 / 0.135.
x ≈ 12000.
Therefore, Liza deposited $12,000 at 2.5% interest, and twice as much, or $24,000, at 5.5% interest.