Step-by-step explanation
From the given question
We are given the formula to compute the amount that a sum of $8000 compounded quarterly will yield after time t at a rate of 2.8%
The formula is given by

Part A

part B
the amount in the account after 7 years will be

The amount that will be in the account after 7 years will be $9725.57
Part C
APY is given by
In our case we have

Hence, we will have the APY as

Hence, the APY is 2.829%