Fred has a piggy bank. On his twelfth birthday, he started saving money. Every week, on the first day of the week, he puts half of his $ 40 allowance into the bank. Write a formula for $f(t)$, the amount of money in his piggy bank $t$ days after his twelfth birthday, on the domain $0 \leq t \leq 28$. You may assume that Fred's first deposit was made on his birthday, i.e. on day $t=0$, which is on the first day of the week.

a) Fill in the missing values in the table below.

$t$	0	4	7	9	14	20	21	25	28
$f(t)$

b) Which of the following graphs is a graph of the function $f(t)$? ? A B C D

A		B		C		D

Hint: