1. What should be the annual interest rate (percentage) for a principal amount to become three times its original value in 25 years?

2. At an annual simple interest rate of 18%, in how many years will a principal amount become 6 times its original value?

(a) 25 years (b) 30 years (c) 31.78 years (d) 27.78 years

3. At an annual simple interest rate of 8%, how much interest will make the principal amount grow to \(\cfrac{7}{5}\) times its original value?

(a) 4 years (b) 5 years (c) 6 years (d) 7 years

4. If the ratio of the principal amount to its increased value after one year is 25:27, then what will be the annual interest rate?

(a) 2% (b) 4% (c) 6% (d) 8%

5. If a certain amount of money doubles in \(n\) years under a fixed annual compound interest rate, in how many years will it become 4 times its original value?

6. Determine how many years it will take for an amount to become eight times its original value under a fixed annual compound interest rate, given that it doubles in \(n\) years.

7. At a simple interest rate of \(6\cfrac{1}{4}\%\) per annum, a principal will become three times its original value.

(a) 16 years (b) \(16\cfrac{2}{3}\) years (c) 20 years (d) 32 years

8. If a principal amount becomes 3 times its original value in 8 years with interest, when will it become 5 times its original value?

(a) 12 years (b) 15 years (c) 16 years (d) 20 years

9. At what annual interest rate will the interest on a principal amount become \(\cfrac{5}{16}\) of the principal in 6\(\cfrac{1}{4}\) years?

(a) 3% (b) 4% (c) 5% (d) 6%

10. If a sum of money becomes 4 times its original amount in *n* years at a fixed annual compound interest rate, then in how many years will it become 4 times?

11. A farmer deposited some money in the village post office. After 4 years, he found that the total amount including interest had become ₹434. He calculated that the interest he received was \(\frac{6}{25}\) of his principal amount. Find how much money he had originally deposited and what annual rate of simple interest the post office gave.

12. At an annual compound interest rate of 5%, what principal amount will yield ₹315.25 as compound interest in 3 years?

13. If a certain principal amount becomes 5 times its original value in 20 years due to interest, then the rate of interest is –

(a) 20% (b) 25% (c) 15% (d) 10%

14. At an annual compound interest rate of 5%, what principal amount will yield a compound interest of 615 currency units in 2 years?

15. At an annual interest rate of \(6\frac{1}{2}\%\), in how much time will the compounded principal amount become 1.5 times the original principal?

16. In compound interest, if an amount becomes \(\cfrac{27}{8}\) times the principal in 3 years, what will be the annual rate of interest? Let me know if you'd like the full solution as well—I'm ready when you are.

17. Aman borrowed ₹25,000 for 3 years, with annual compound interest rates of 4% for the first year, 5% for the second year, and 6% for the third year. What amount will Aman repay (including principal and interest) at the end of 3 years?

18. What annual compound interest rate will make a principal amount grow \(\cfrac{27}{8}\) times in 3 years?

19. If a principal becomes \(3\frac{3}{8}\) times the original amount in 3 years at compound interest, what is the annual rate of interest?

20. A principal amount doubles in 20 years at a certain simple interest rate. At the same rate of simple interest, the time required for the principal to become three times will be:

(a) 30 Years (b) 35 Years (c) 40 Years (d) 45 Years

21. If the time period and the annual simple interest rate are equal, then at what annual interest rate will the interest amount be \(\cfrac{1}{25}\) of the principal?

(a) 25% (b) 10% (c) 2% (d) 2.5%

22. At what annual percentage rate of interest will a principal amount double in 16\(\cfrac{2}{3}\) years?

(a) 4% (b) 5% (c) 6% (d) 8%

23. Some money becomes 5 times its original amount in 5 years at simple interest. At the same rate of interest, the time required for that principal to become 17 times is:

(a) 17 years (b) 20 years (c) 18 years (d) 19 years

24. At an annual simple interest rate of 6%, in how many years will the interest on ₹\(x\) amount become ₹\(\frac{9x}{25}\)? Find the value of the time.

(a) 6 years (b) 8 years (c) 10 years (d) 12 years

25. What should be the annual rate of simple interest (in percentage) so that the interest earned in 4 years becomes \(\frac{8}{25}\) of the principal amount?

26. What should be the annual compound interest rate for a certain amount of money to become 1.96 times that amount in 2 years?

27. If a principal amount doubles in 8 years at an annual compound interest rate of \(r\%\), then in how many years will it become four times?

28. At an annual interest rate of 4%, what principal amount will yield at least ₹80 difference between simple interest and compound interest over 2 years?

29. A farmer deposits ₹100 at the post office on the first day of every month. If the annual rate of simple interest is 5%, what will be the total amount (principal + interest) he receives at the end of the year?

30. If the ratio of a principal amount to its annual amount with interest is 20:25, then the annual interest rate will be 4%.