Annual contributions of $1000 will be made to a TFSA for 25 years. The contributor expects investments

Question:

Annual contributions of $1000 will be made to a TFSA for 25 years. The contributor expects investments within the plan to earn 7% compounded annually. What will the TFSA be worth after 25 years if the contributions are made:
a. At the end of each year?
b. At the beginning of each year?
c. By what percentage does the answer to Part (b) exceed the answer to Part (a)?