Answer:
$5599.20
Step-by-step explanation:
The quarterly interest rate for the first two years was ...
7%/4 = 0.0175
So, the multiplier each quarter for those 8 quarters was 1+0.0175 = 1.0175. At the end of the first 8 quarters, the account value had been multiplied by ...
1.0175^8
For the next 8 quarters, the quarterly interest rate was 10%/4 = 0.025. So at the end of those 8 quarters, the balance had been multiplied by ...
1.025^8
Then the balance at the end of 4 years was ...
$4000(1.0175^8)(1.025^8) ≈ $5599.20
The balance was $5599.20.