Simple Interest | Find Teacher Post Worksheets - Free Printable

Certainly! Let’s solve each problem step by step using the Simple Interest formula:

> Simple Interest (SI) = (P × R × T) / 100
>
> Where:
> - P = Principal (initial amount invested)
> - R = Rate of interest per annum (in %)
> - T = Time in years
> - Total Amount (A) = P + SI

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Problem 1: Calculate

#### a. Simple interest on ₹1200 for 3 years at 6% per annum

- P = ₹1200
- R = 6%
- T = 3 years

SI = (1200 × 6 × 3) / 100
= (21600) / 100
= ₹216

✔ Answer: ₹216

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#### b. Simple interest on ₹700 for 6 months at 8.25% per annum

Note: Time is in months, so convert to years:
6 months = 6/12 = 0.5 years

- P = ₹700
- R = 8.25%
- T = 0.5 years

SI = (700 × 8.25 × 0.5) / 100
First, calculate numerator:
700 × 8.25 = 5775
5775 × 0.5 = 2887.5

Now divide by 100:
SI = 2887.5 / 100 = ₹28.875

We usually round money to two decimal places:
✔ Answer: ₹28.88

*(Note: In some contexts, especially school problems, they may expect ₹28.87 or exact fraction — but ₹28.88 is standard rounding.)*

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#### c. The length of time for ₹5000 to earn ₹1000 if invested at 10% per annum

We are given:
- SI = ₹1000
- P = ₹5000
- R = 10%
- T = ?

Use formula: SI = (P × R × T)/100

Plug in values:
1000 = (5000 × 10 × T) / 100

Simplify right side:
(5000 × 10 × T) / 100 = (50000 × T) / 100 = 500 × T

So:
1000 = 500 × T
→ T = 1000 / 500 = 2 years

✔ Answer: 2 years

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Problem 2: Khalid invests ₹6750 at 8.5% per annum. How much interest has been earned and what is the total amount in his account after 4 years?

- P = ₹6750
- R = 8.5%
- T = 4 years

SI = (6750 × 8.5 × 4) / 100

Step-by-step:

First, 6750 × 8.5 = ?

Break it down:
6750 × 8 = 54,000
6750 × 0.5 = 3,375
Total = 54,000 + 3,375 = 57,375

Now multiply by 4:
57,375 × 4 = 229,500

Now divide by 100:
SI = 229,500 / 100 = ₹2295

Total Amount = P + SI = 6750 + 2295 = ₹9045

✔ Interest earned: ₹2295
✔ Total amount after 4 years: ₹9045

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Problem 3: Shamen invests ₹10000. After 4 years she has earned ₹3240 in interest. At what annual rate of interest did she invest the money?

Given:
- P = ₹10000
- T = 4 years
- SI = ₹3240
- R = ?

Use formula: SI = (P × R × T)/100

Plug in:
3240 = (10000 × R × 4) / 100

Simplify right side:
(10000 × 4 × R) / 100 = (40000 × R) / 100 = 400 × R

So:
3240 = 400 × R
→ R = 3240 / 400 = 8.1

✔ Answer: 8.1% per annum

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## ✔ Final Answers Summary:

1. a. ₹216
1. b. ₹28.88
1. c. 2 years

2. Interest = ₹2295; Total Amount = ₹9045

3. Rate = 8.1% per annum

Let me know if you’d like these explained with diagrams or further examples!