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Question

In what duration of time will \(₹3300\) become \(₹3399\) at 12% per annum interest compounded quarterly ?

This question was previously asked in
CDS 2 2026 Maths Question Paper (13-Sep-2026)
The correct answer is

3 months

To find out in what duration of time ₹3300 will become ₹3399 at 12% per annum interest compounded quarterly, we will use the compound interest formula:

\(A = P \left(1 + \frac{r}{n}\right)^{nt}\)

Where:

  • \(A\) = the final amount = ₹3399
  • \(P\) = the principal amount = ₹3300
  • \(r\) = annual interest rate = 12% = 0.12
  • \(n\) = number of times interest is compounded per year = 4 (quarterly)
  • \(t\) = the time in years = ?

Substituting the known values into the formula:

\(3399 = 3300 \left(1 + \frac{0.12}{4}\right)^{4t}\)

\(3399 = 3300 \left(1 + 0.03\right)^{4t}\)

\(3399 = 3300 \times (1.03)^{4t}\)

To find \(4t\), divide both sides by 3300:

\(\frac{3399}{3300} = (1.03)^{4t}\)

\(1.03 = (1.03)^{4t}\)

Since \(1.03 = (1.03)^1\), we have:

\(4t = 1\)

Now solving for \(t\):

\(t = \frac{1}{4} \text{ year} = 3 \text{ months}\)

The correct answer is that the duration of time required is 3 months.

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Important Questions from Interest

  1. The difference between compound interest and simple interest on an amount of Rs.25,000 for 2 years is Rs.250. What is the rate of interest per annum? (In %)
  2. Increase in Debt-Equity ratio in a firm __________ to equity holders.
  3. The difference between the compound interest and simple interest on a certain amount at 5%per annum for 2 years is Rs. 15.The principal amount is equal to :

  4. Dhoni invested Rs 22000 at 12% simple interest per annum and Rs 15000 at 10% compound interest per annum, then find the total amount earned by him at the end of 2 years.

  5. The difference between the compound interest and the simple interest on a sum of Rs. 8,000 for 2 years at the rate of 5% p.a. is:

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