1. If a principal amount doubles in 10 years, what will be the annual simple interest rate ?

(a) 5% (b) 10% (c) 15% (d) 20%

2. If the amount becomes ₹\(y\) in \(x\) years at an annual interest rate of 4%, then the principal (original amount) will be –

(a) ₹ \(4xy\) (b) ₹\(\cfrac{4x}{100+y}\) (c) ₹ \(\cfrac{100y}{100+4x}\) (d) ₹\(\cfrac{100x}{4}\)

3. If a principal amount doubles in 10 years, the annual simple interest rate will be 20%.

4. If a principal amount doubles in 10 years, the annual interest rate will be _____.

5. If the total amount becomes 966 rupees at an annual simple interest rate of 3% in 5 years, the principal amount will be -

(a) 480 rupees (b) 408 rupees (c) 404 rupees (d) 840 rupees

6. If the interest on a principal for 5 years is \(\cfrac{1}{4}\) of the principal, then the annual interest rate will be –

(a) 5% (b) 10% (c) 15% (d) 20%

7. 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%

8. ₹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

9. 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?

10. 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.

11. A borrowed ₹960 from B at an annual simple interest rate of 6%, with the condition that the loan will be repaid over the next 4 yearly installments. In the first 3 installments, A will pay only one-fourth of the principal each year. In the final (4th) installment, A will pay the remaining principal along with the total interest accrued over the 4 years. Find the total amount A will pay at the end of the 4th year.

12. If the ratio of principal to amount after 1 year is 4:9, then the annual simple interest rate will be 5%.

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

14. 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.

15. 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.

16. 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?

17. 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?

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

19. 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

20. 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

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 the interest on an amount in 4 years become \(\cfrac{1}{6}\) of the total amount?

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

23. What will be the total amount of 450 rupees after 3 years at an annual simple interest rate of 4%?

(a) ₹ 135 (b) ₹ 180 (c) ₹ 504 (d) ₹ 600

24. If a principal amount doubles in 10 years, then the annual simple interest rate is—?

(a) 5% (b) 10% (c) 15% (d) 20%

25. 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

26. If a certain principal amount triples in 15 years at simple interest, then the annual rate of simple interest will be —

(a) \(13\frac{1}{3}\%\) (b) \(12\frac{1}{3}\%\) (c) \(11\frac{1}{3}\%\) (d) \(10\frac{1}{3}\%\)

27. 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?

28. 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?

29. What should be the annual rate of simple interest (in percentage) so that the interest earned in 4 years becomes \( \frac{2}{5} \) of the principal amount?

30. 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?