What I am contributing is helping the student understand that their confusion is perfectly understandable. The student’s teacher eeither knows nothing about finance or knows nothing about the English language (or probably knows nothing about both). However you define capital, it does not have agency; it does not raise money by going to the bank or floating stock on a bourse. Nor does it open a savings account at a building society. Those are activities that human actors engage in. So the sentence is practical nonsense from its subject to its final period.
Although there are many forms in which capital is treated legally, the ones most common in Europe and North America are debt and equity. And most forms of equity do not have a constant return to which the mathematics of annuities, etc. apply. Thus, for anyone who actually knows something about how finance is conducted in most of the commercial world, defined rates of return are associated with debt. And debt has periodic payments if it involves maturities measured in decades. (You might try getting your bank to lend you money without a single payment of interest or principal for just a single decade.)
Students who study the mathematics of finance do so with some limited understanding of the mechanics and vocabulary of lending in the real commercial world. Problems that violate that understanding do not help students. I had a career in finance for 43 years, and I have no idea what actual situation that problem contemplates. That makes it extremely difficult to construct a reasonable mathematical model to use.
You have suggested reverse engineering from the given answer to determine what the teacher intended to ask. This hardly teaches how to use mathematics to find answers. Moreover, it is not clear that any answer was provided on which to do reverse engineering. Maybe the teacher should have made the effort and taken the time to pose a question from which an answer can be derived rather than vice versa.
