Final answer:
To calculate the principal at the end of 10 years with quarterly compounding interest, we can use the formula A = P(1 + r/n)^(nt). For this question, P = 15000, r = 0.12 (12%), n = 4 (quarterly compounding), and t = 10.
Step-by-step explanation:
To calculate the principal at the end of 10 years with quarterly compounding interest, we can use the formula:
A = P(1 + r/n)^(nt)
Where:
- A is the amount at the end of the time period
 - P is the principal amount
 - r is the annual interest rate (in decimal form)
 - n is the number of times the interest is compounded per year
 - t is the number of years
 
For this question, P = 15000, r = 0.12 (12%), n = 4 (quarterly compounding), and t = 10. Plugging in these values into the formula:
A = 15000(1 + 0.12/4)^(4 * 10)