1. If the annual rate of interest and the time in years are equal, then in how many years will the interest on ₹324 amount to ₹16?

(a) \(2\cfrac{2}{9}\) (b) \(2\cfrac{1}{9}\) (c) \(2\cfrac{4}{9}\) (d) \(2\cfrac{5}{9}\)

2. 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

3. At an annual interest rate of 5%, for how many years will the interest on 300 rupees amount to 120 rupees?

(a) 4 (b) 8 (c) 12 (d) 12\(\frac{1}{2}\)

4. 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%

5. 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?

6. 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?

7. 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?

8. At an annual interest rate of 4%, for how much money will the difference between the simple interest and the compound interest for 2 years be 80 rupees? Let’s calculate and write it down.

9. 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

10. What time period will yield the same interest as 10000 rupees at 10% for 20 years, when invested at 8% on 25000 rupees?

(a) 8 years (b) 10 years (c) 12 years (d) 15 years

11. ₹1200 is lent at an annual interest rate of 6\(\frac{1}{4}\)% and ₹1000 is lent at an annual interest rate of 4\(\frac{1}{3}\)% on the same day. After how much time will the amounts (principal + interest) of both loans become equal?

(a) 20 years (b) 24 years (c) 15 years (d) 30 years

12. 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?

13. 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.

14. If the principal is \(p\) rupees and the annual compound interest rates for the first, second, and third years are \(r_1\%\), \(r_2\%\), and \(r_3\%\) respectively, then what will be the total compound amount after 3 years?

15. 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.

16. Rahmat Chacha borrowed ₹240000 from a bank at an annual simple interest rate of 12% to build a house. One year after borrowing, he started renting out the house for ₹5200 per month. Calculate and determine after how many years from borrowing he will be able to repay the bank loan along with interest using the rental income.

17. Mr. Rathin deposits money in the bank for each of his two daughters in such a way that when each daughter turns 18 years old, she will receive ₹120000. The bank offers simple interest at an annual rate of 10%. The current ages of the daughters are 13 years and 8 years respectively. Calculate how much Mr. Rathin deposited in the bank for each daughter.

18. Some money amounts to 944 rupees in 3 years at simple interest. If the annual rate of interest increases by 25%, then the same money amounts to 980 rupees in the same time. Find the rate of interest and the principal.

19. If the interest is compounded semi-annually, what will be the compound amount on ₹10,000 for \(1\cfrac{1}{2}\) years, where the annual compound interest rates are 10% for the first period, 20% for the second period, and 40% for the third period?

20. In how many years will the ratio of the principal and the interest earned become 10:3 at a simple interest rate of 10% per annum?

(a) 12 years (b) 3 years (c) 10 years (d) 13 years

21. 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

22. If the simple interest on ₹850 for 3 years and on ₹1250 for 4 years at the same rate amounts to ₹302 in total, then what will be the annual rate of interest?

(a) 3% (b) 5% (c) 7% (d) None of the above

23. 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?

24. A certain sum of money amounts to ₹944 in 3 years at simple interest. If the rate of interest is increased by 25%, the same sum amounts to ₹980 in the same time period. Find the principal amount and the original rate of interest.

25. 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

26. If the total simple interest on a principal amount at an annual rate of \(x\%\) for \(y\) years is \(\frac{pyx}{25}\) rupees, then the principal amount will be:

(a) \(2p\) rupees (b) \(4p\) rupees (c) \(\cfrac{p}{2}\) rupees (d) \(\cfrac{p}{4}\) rupees

27. In how many years, at the rate of 8% per annum, will the ratio of the principal to the simple interest become 25 : 8?

(a) \(3\cfrac{1}{2}\) (b) 4 (c) 5 (d) \(5\cfrac{1}{2}\)

28. 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.

29. If the annual interest rates for ₹8000 in the first and second years are 9% and 10% respectively, then the amount after 2 years including interest will be –

(a) ₹ 9295 (b) ₹9952 (c) ₹ 9259 (d) ₹ 9592

30. My uncle borrowed ₹40,000 for 3 years in such a way that the annual compound interest rates for the first, second, and third years were 2%, 3%, and 4% respectively. How much money will he repay (principal + interest) at the end of 3 years?