Answer:
a. number of periods over which interest is calculated on the loan
Step-by-step explanation:
A formula should always be accompanied by an explanation of what it calculates and the meaning of each of its variables. This formula calculates P, the periodic payment on a loan of n periods at interest rate i (compounded) per period. The principal amount of the loan is PV.
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The same formula can also be used to calculate an annuity from which payment P is received at the end of each of n periods. The amount invested is PV and the interest rate per period (compounded per period) is i.