Answer
1.63 billion dollars
Work Step by Step
The flow of rate of the investment stream can be expressed as: $R(t)=0.273 \times (1+\dfrac{10}{100})^t=0.273 (1.10)^t$ billion dollars per year.
We have: $r=0.13$ and $T=15 \ years$
The future value is equal to: $\int_0^{15} 0.273 (1.10)^te^{-0.15t} \ dt =1.63$ billion dollars