1. If a certain amount of money doubles in \(n\) years at a fixed annual compound interest rate, then in how many years will it become four times?

2. If a certain amount of money doubles in 4 years at a fixed annual compound interest rate, in how many years will it become four times?

3. 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?

4. If a sum of money doubles in \(n\) years at a fixed annual compound interest rate, then in how many years will it become 4 times?

5. If a certain amount of money doubles in \(n\) years at an annual compound interest rate, determine in how many years it will become eight times.

6. 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

7. If a certain amount of money triples in 7 years at an annual compound interest rate, in how many years will it become 9 times?

(a) 10 (b) 12 (c) 14 (d) 13

8. 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?

9. If a sum of money doubles in \(n\) years at an annual compound interest rate, then it will become four times in –

(a) \(2n\) years (b) \(\cfrac{n}{2}\) years (c) \(3n\) years (d) \(\cfrac{n}{3}\) years

10. If ₹27,500 doubles in 6 years at compound interest, then in how many years will it become four times?

(a) 16 (b) 15 (c) 12 (d) 10

11. 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.

12. If a principal amount doubles in 4 years at a compound interest rate of \(r\%\), then it will become 4 times in ______ years.

13. If a principal amount is invested at an annual simple interest rate of 6%, in how many years will it double?

14. If a certain amount of money triples in 11 years at a fixed interest rate, in how many years will it become five times?

(a) 12 years (b) 6 years (c) 20 years (d) 22 years

15. In how many years will the amounts of simple interest and compound interest be equal for the same principal at the same annual interest rate?

(a) 3 years (b) 2 years (c) 1 years (d) \(\frac{1}{2}\)

16. If a principal amount doubles in 20 years at a certain simple interest rate, then in how many years will it triple at the same simple interest rate?

17. At an annual compound interest rate of 4%, in how many years will a principal amount of ₹40,000 accumulate to ₹46,656?

18. A principal amount doubles in 20 years at a certain simple interest rate. At the same rate, in how many years will the principal become three times?

19. 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.

20. Write down the calculation to determine in how many years a simple interest of ₹168 will be earned on a principal of ₹600 at an annual rate of 8%.

21. I have ₹5000. I deposited this amount in a bank at an annual compound interest rate of 8.5%. Write the calculation to determine the total amount (principal + interest) I will receive after 2 years.

22. Write the calculation to determine the principal amount for which the compound interest for 3 years at an annual compound interest rate of 10% will be ₹2648.

23. If the simple interest and compound interest on a certain principal for 2 years are ₹8400 and ₹8652 respectively, then calculate and write the amount of the principal and the annual rate of interest.

24. Let us determine in how many years ₹40000 will amount to ₹46656 at an annual compound interest rate of 8%.

25. Calculate and write in how many years ₹300000 will amount to ₹399300 at an annual compound interest rate of 10%.

26. If the simple interest and compound interest on a certain principal for 2 years are 840 rupees and 869.40 rupees respectively, then let’s calculate and write down the principal amount and the annual rate of interest.

27. At an annual compound interest rate of 10%, in how many years will ₹4000 amount to ₹5324? Let’s calculate and write it down.

28. At an annual simple interest rate of 5%, how many years will it take for the interest on ₹6000 to become ₹1500?

(a) 3 years (b) 30 years (c) 5 years (d) 15 years

29. If the annual simple interest on a principal is \(\cfrac{1}{9}\) of it, then what will be the accumulated amount in 4 years if the total sum becomes 1326 rupees?

(a) ₹ 1080 (b) ₹ 1120 (c) ₹ 918 (d) ₹ 750

30. 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