On a certain sum of money, after 2 years the simple interest and compo...
400 = P*(R/100)*2
600 = P*(1+R/100)2 – P
Solve both equations to get P
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On a certain sum of money, after 2 years the simple interest and compo...
400 = P*(R/100)*2
600 = P*(1+R/100)2 – P
Solve both equations to get P
On a certain sum of money, after 2 years the simple interest and compo...
Given:
Simple Interest after 2 years = Rs 400
Compound Interest after 2 years = Rs 600
To find:
The sum of money invested
Solution:
Let the principal amount be 'P' and the rate of interest be 'r'.
Using the formula for simple interest, we have:
SI = (P * r * t) / 100
Here, t = 2 years
Therefore, 400 = (P * r * 2) / 100
Using the formula for compound interest, we have:
CI = P * (1 + r/100)^t - P
Here, t = 2 years
Therefore, 600 = P * (1 + r/100)^2 - P
Simplifying the above equations, we get:
400 = 2Pr/100
600 = P[(1 + r/100)^2 - 1]
Dividing the second equation by the first, we get:
(3/2) = (1 + r/100)^2 / r
Let (1 + r/100) = x
Then, (3/2) = x^2 / (x - 1)
3x - 2x^2 = 2
2x^2 - 3x + 2 = 0
Using the quadratic formula, we get:
x = (3 ± √(9 - 16)) / 4
x = (3 ± i) / 4
Here, i is the imaginary unit.
Since the interest rates cannot be negative or imaginary, we take only the positive root:
x = (3 + i) / 4
1 + r/100 = (3 + i) / 4
r/100 = (3 + i) / 4 - 1
r/100 = (3 - i) / 4
r = (300 - i100) / 4
r = 75 - i25
Substituting this value of 'r' in the equation for simple interest, we get:
400 = (P * 75 * 2) / 100
P = Rs 200
Therefore, the sum of money invested is Rs 200.
Answer: Option B) 200