Answer
$$ Final \ Year: \ \$30,418 \\ Total: \ $99,868$$
Work Step by Step
The amount earned in the final year is:
$$ = (20000)(1.15^3) \\ = \$30,418$$
The total amount earned is:
$$ = 20000+(20000)(1.15)+(20000)(1.15^2)+20000(1.15^3) \\ = \$99,868$$
