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cfc198
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The compound interest earned in the 3rd and 4th year is Rs. 450 and Rs 11 May 2019, 08:34
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C
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71% (01:50) correct 29% (02:13) wrong based on 228 sessions

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The compound interest earned in the 3rd and 4th year is 450$ and 500$. Find the rate of interest.

1. 9.09%
2. 10%
3. 11.11%
4. 12.5%
5. 15%
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C
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The compound interest earned in the 3rd and 4th year is Rs. 450 and Rs 11 May 2019, 20:13
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cfc198
The compound interest earned in the 3rd and 4th year is 450$ and 500$. Find the rate of interest.

1. 9.09%
2. 10%
3. 11.11%
4. 12.5%
5. 15%
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Amount after 3 years is \(P(1+\frac{r}{100})^3=450\)..
After 4 yrs = \(P(1+\frac{r}{100})^4=500\)....... \(P(1+\frac{r}{100})^3*(1+\frac{r}{100})=500\)......
\(450(1+\frac{r}{100})=500.....4.5r=50......r=50/4.5=100/9=11.11\)..

C
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The compound interest earned in the 3rd and 4th year is Rs. 450 and Rs 11 May 2019, 22:08
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For 4th year, principal 450, interest 50,
Interest rate =
450 is 100
50 is ?
% = 50/450*100 = 11.11%.

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The compound interest earned in the 3rd and 4th year is Rs. 450 and Rs 12 Mar 2022, 05:01
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chetan2u
cfc198
The compound interest earned in the 3rd and 4th year is 450$ and 500$. Find the rate of interest.

1. 9.09%
2. 10%
3. 11.11%
4. 12.5%
5. 15%

Amount after 3 years is \(P(1+\frac{r}{100})^3=450\)..
After 4 yrs = \(P(1+\frac{r}{100})^4=500\)....... \(P(1+\frac{r}{100})^3*(1+\frac{r}{100})=500\)......
\(450(1+\frac{r}{100})=500.....4.5r=50......r=50/4.5=100/9=11.11\)..

C
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I think the problem states the interest accrued is 450$, not the amount. Although it is inherently the same here, for precision I would say that we should not multiply P by (1+r)^3. We should just understand that that 450$-s earned us extra 50$ in the 4th year. That gives us 50/450=1/9=11.11%.
Am I right with this reasoning?

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The compound interest earned in the 3rd and 4th year is Rs. 450 and Rs 05 Apr 2022, 02:59
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The question simply states that the SI on 450 is 50.
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The compound interest earned in the 3rd and 4th year is Rs. 450 and Rs 09 May 2025, 13:55
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Hi...can someone pls post correct explanation as the q says interest , not total amount...so actually :

P[ (1+ r/100)^3 -1] = 450
P[(1 + r/100)^4 -1] = 500

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The compound interest earned in the 3rd and 4th year is Rs. 450 and Rs 11 May 2025, 21:04
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cfc198
The compound interest earned in the 3rd and 4th year is 450$ and 500$. Find the rate of interest.

1. 9.09%
2. 10%
3. 11.11%
4. 12.5%
5. 15%
Show more
CI in two consecutive years differs only by interest on interest of previous year.
So in 3rd year interest was 450.
In 4th year, interest would be 450 + r% of 450 (where r is the rate of interest)

Hence r% of 450 = 50
which means r = 1/9 = 11.11%

Answer (C)

Here is the explanation of this concept: https://www.youtube.com/watch?v=pfjZE2xcf04
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The compound interest earned in the 3rd and 4th year is Rs. 450 and Rs 12 May 2025, 22:52
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We are given:

* Compound Interest (CI) for the **3rd year** = \$450
* CI for the **4th year** = \$500
* We are to **find the rate of interest $r$%**.

---

### 💡 Key Concept:

In **compound interest**, the interest for each year is calculated on the **amount of the previous year**, so:

$$
\text{CI for 4th year} = \text{CI for 3rd year} \times \left(1 + \frac{r}{100}\right)
$$

So,

$$
500 = 450 \times \left(1 + \frac{r}{100}\right)
$$

---

### 🧮 Solve for $r$

$$
\frac{500}{450} = 1 + \frac{r}{100}
$$

$$
\frac{10}{9} = 1 + \frac{r}{100}
$$

$$
\frac{10}{9} - 1 = \frac{r}{100}
$$

$$
\frac{1}{9} = \frac{r}{100}
$$

Multiply both sides by 100:

$$
r = \frac{100}{9} \approx 11.11\%
$$

✅ Final Answer: **3. 11.11%**
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