Monica Lane maintains a savings deposit with Monarch Credit Union. This past year Monica received $10.75 in interest earnings from her savings account. Her savings deposit had the following average balance each month:
| January | $400 | July | $350 |
| February | 250 | August | 425 |
| March | 300 | September | 550 |
| April | 150 | October | 600 |
| May | 225 | November | 625 |
| June | 300 | December | 300 |
What was the annual percentage yield (APY) earned on Monica’s savings account?
Monica’s account had an average balance this year of:
[$400 x 31 days + $250 x 28 days + $300 x 31 days + $150 x 30 days
+ $225 x 31 days + $300 x 30 days + $350 x 31 days + $425 x 31 days + \frac{\$ 550 \times 30 \text { days }+\$ 600 \times 31 \text { days }+\$ 625 \times 30 \text { days }+\$ 300 \times 31 \text { days }]}{365 \text { days }}
= $373.56
Then the APY must be:
A P Y=100\left[\left(1+\frac{\$ 10.75}{\$ 373.56}\right)^{365 / 365}-1\right]=2.88 \text { percent }