ANSWER and EXPLANATION
We want to find the value of f(22) for:
To do this, substitute 22 for t in the given function. That is:
That is the value of f(22)
As regards investing, this value simply indicates that if an amount of money (e.g. $2000) is invested at an interest rate (e.g. 0.05 or 5%) for a certain period of time (e.g. 22 years), there will be a reasonable increment in the total amount after the time has elapsed.