Simple interest and compound interest (compounding annually) on a principal at…

2024

Simple interest and compound interest (compounding annually) on a principal at a certain rate of interest for 2 years is Rs. 28800 and Rs. 36000 respectively. What is the principal?

  1. A.

    Rs. 30000

  2. B.

    Rs. 28800

  3. C.

    Rs. 29750

  4. D.

    Rs. 28850

Attempted by 10 students.

Show answer & explanation

Correct answer: B

To find the principal amount, we can use the specific relationship between Simple Interest (SI) and Compound Interest (CI) for a period of 2 years.

Step-by-Step Calculation
Understand the difference:

SI for 2 years = 28,800

CI for 2 years = 36,000

The difference between CI and SI for 2 years is the interest earned on the first year's interest.

Difference = 36,000 - 28,800 = 7,200

Calculate the Interest Rate (R):

SI for 2 years is 28,800, so SI for 1 year = 28,800 / 2 = 14,400.

The difference of 7,200 is essentially the interest on the first year's SI (14,400).

Rate (R) = (Difference / SI for 1 year) × 100

R = (7,200 / 14,400) × 100 = 50%

Calculate the Principal (P):

Use the Simple Interest formula: SI = (P × R × T) / 100

28,800 = (P × 50 × 2) / 100

28,800 = (P × 100) / 100

P = 28,800

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