Answer:
In 2050, the predicted expenditure will be $15,315 billion.
Step-by-step explanation:
We are given the following in the question:

where E(X) is the total annual expenditure in billions of dollar and x is the number of years past 2000.
We have to estimate the year in which predicted expenditure will be $15,315 billion.
Putting values in the question:

Thus, after 50 years from 2000, the predicted expenditure will be $15,315 billion.
Thus, in year 2050, the predicted expenditure will be $15,315 billion.