Final answer:
The correct variables for the compound interest formula are P for Principal, r for Rate, n for the Number of times interest is compounded per year, and t for Time. The compound interest is found by finding the difference between the future value and the principal.
Step-by-step explanation:
The variables in the compound interest formula when the interest is paid more than once a year are:
So, the correct answer is c) P - Principal, r - Rate, n - Number of times interest is compounded, t - Time.
To calculate the compound interest, you need to find the difference between the future value and the present value of the principal. The formula for the future value (FV) is:
FV = P x (1 + r/n)nt
Compound interest is then found by subtracting the principal (P) from the future value (FV):
Compound Interest = FV - P