Answer
$$ \$274473.93$$
Work Step by Step
Since $$ R(0)=70000,\ r=0.05 \ \to \ R(t) =70000e^{0.05t} $$
Then for $T=4 ,\ r=0.06 $
\begin{align*}
P V&=\int_{0}^{4} 70000 e^{-0.01 t} d t\\
&=\left.\frac{70000}{-0.01} e^{-0.01 t}\right|_{0} ^{4}\\
&=-7000000\left(e^{-0.04}-e^{0}\right) \\
&\approx \$274473.93
\end{align*}
