10 important Simple Interest (S.I.) questions with solutions,

Here are 10 important Simple Interest (S.I.) questions with solutions, useful for Coal India exams and other competitive exams:

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1. Finding Simple Interest

Q: Find the Simple Interest on ₹5,000 at 10% per annum for 3 years.

Solution:

S.I. = \frac{P \times R \times T}{100}

= \frac{5,000 \times 10 \times 3}{100} = \frac{1,50,000}{100} = 1,500 ] So, S.I. = ₹1,500.

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2. Finding Total Amount (Principal + Interest)

Q: A loan of ₹8,000 is taken at 12% per annum for 4 years. Find the total amount to be paid.

Solution:

S.I. = \frac{P \times R \times T}{100} = \frac{8,000 \times 12 \times 4}{100} = 3,840

\text{Total Amount} = P + S.I. = 8,000 + 3,840 = 11,840 ] So, Total Amount = ₹11,840.

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3. Finding Rate of Interest

Q: ₹6,000 becomes ₹7,200 in 2 years. Find the rate of interest.

Solution:

S.I. = A - P = 7,200 - 6,000 = 1,200

R = \frac{S.I. \times 100}{P \times T} = \frac{1,200 \times 100}{6,000 \times 2} = \frac{1,20,000}{12,000} = 10% ] So, Rate of Interest = 10% per annum.

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4. Finding Principal

Q: The Simple Interest is ₹1,800 on a loan for 3 years at 6% per annum. Find the principal.

Solution:

P = \frac{S.I. \times 100}{R \times T} = \frac{1,800 \times 100}{6 \times 3} = \frac{1,80,000}{18} = 10,000

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5. Finding Time

Q: A sum of ₹2,500 earns ₹750 as Simple Interest at 5% per annum. Find the time period.

Solution:

T = \frac{S.I. \times 100}{P \times R} = \frac{750 \times 100}{2,500 \times 5} = \frac{75,000}{12,500} = 6 \text{ years}

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6. Double the Principal

Q: In how many years will ₹5,000 become ₹10,000 at 10% per annum?

Solution:

Since the amount doubles,

A = 2P \Rightarrow S.I. = P

T = \frac{S.I. \times 100}{P \times R} = \frac{5,000 \times 100}{5,000 \times 10} = \frac{5,00,000}{50,000} = 10 \text{ years} ] So, Time = 10 years.

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7. Bank Loan Interest

Q: A coal supplier takes a loan of ₹15,000 at 8% per annum for 5 years. Find the Simple Interest.

Solution:

S.I. = \frac{P \times R \times T}{100} = \frac{15,000 \times 8 \times 5}{100} = 6,000

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8. Interest Difference Calculation

Q: Find the difference between Simple Interest for 5 years and 6 years on ₹12,000 at 7% per annum.

Solution:

S.I. (5 \text{ years}) = \frac{12,000 \times 7 \times 5}{100} = 4,200

S.I. (6 \text{ years}) = \frac{12,000 \times 7 \times 6}{100} = 5,040 ]

\text{Difference} = 5,040 - 4,200 = 840

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9. Farmer's Loan Calculation

Q: A farmer takes a loan of ₹25,000 at 9% per annum for 3 years. Find the total amount to be paid.

Solution:

S.I. = \frac{P \times R \times T}{100} = \frac{25,000 \times 9 \times 3}{100} = 6,750

\text{Total Amount} = 25,000 + 6,750 = 31,750 ] So, Total Amount = ₹31,750.

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10. Investment Profit

Q: A businessman invests ₹18,000 in coal trading at 6.5% per annum. What will be the total profit after 4 years?

Solution:

S.I. = \frac{P \times R \times T}{100} = \frac{18,000 \times 6.5 \times 4}{100} = 4,680

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These Simple Interest questions cover all key formulas and are useful for Coal India exams. Let me know if you need more practice!