Step-by-step explanation:
3)
[tex]7billion = 5 {e}^{15r} \\ 1.4billion = {e}^{15r} \\ ln(1.4 \: billion) = 15r \\ 21.0597 = 15r \\ r = 1.404[/tex]
[tex]4) \\ t = 0 \: y= 200 \\200 = a {e}^{0} \\ a = 200 \\ 800 = 200 {e}^{8k} \\ 4 = {e}^{8k} \\ ln(4) = 8k \\ k = 0.1733[/tex]
