Correct Answer - Option 3 : Rs. 100
Given∶
Some money was invested at the rate of 37% S.I. .
He received Rs. 123 as interest.
And some money was invested at the rate of 43% S.I.
When the amount was interchanged, The interest He received is Rs.(123 - 6) 117.
Formula Used∶
S.I =PRT/100
Basics of Linear Equations.
Calculation∶
Let the amount invested at 37% = Rs. x
And amount invested at 43% = Rs. y
According to Question,
123 = (x × 37 × 1)/100 + ( y × 43 × 1)/100
⇒ 37x + 43 y = 12300 (1)
Also, 117 = (43 × x × 1)/100 + (37 × y × 1)/100
⇒ 43x + 37 y = 11700 (2)
On adding eq.(1) and eq.(2) we get,
x + y = 300 (3)
On subtracting eq.(1) and eq.(2) we get,
y - x = 100 (4)
On adding eq.(3) and eq.(4) we get,
2y = 400
⇒ y = 200 and x = 100
∴ Amount received at 37% is Rs.100.