On the day you were born, your grandfather opened a savings account in your name. At that time, he deposited a certain amount of money into the account, and has deposited the same amount on each of your first 20 birthdays. Today is your 21st birthday. Your grandfather has decided not to make another deposit but rather to give you a special gift. If the account has paid a consistent interest rate of 4% compounded semi-annually and has a current balance of $100,000.

How much money did your grandfather deposit on each occasion? 

Calculate the effective annual interest rate with 4% compounded semi-annually?