Answer
(a) $5665$ dollars
(b) $4.04$ years
(c) $3.96$ years
Work Step by Step
(a) Given $P=5000,r=0.085,n=2,t=1.5$ we have
$A(1.5)=5000(1+\frac{0.085}{2})^{2\times1.5}\approx5665$ dollars
(b) Let $A(t)=7000$, we have $7000=5000(1+\frac{0.085}{2})^{2\times t}$ which gives
$2t=\frac{ln(7/5)}{ln1.0425}\approx8.084$ so $t\approx4.04$ years
(c) In this case, $7000=5000e^{0.085t}$ which gives $t=ln(7/5)/0.085\approx3.96$ years
