Suppose you invested $$4,000$ in a CD on January $1,2017$ maturing in $6$ years that pays interest of $5\%$ per year compounded semiannually and credited at the end of each six month period. You don't withdraw any money from the CD during its term.

$($a$)$ How much money will be in the CD account on January $1,2023?$

$($b$)$ What is the effective annual rate of interest on this CD$?$