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?
- A.
Rs. 30000
- B.
Rs. 28800
- C.
Rs. 29750
- 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