Question

A man earns 6% SI on his deposits in Bank A while he earns 8% simple interest on his deposits in Bank B. If the total interest he earns is Rs.1800 in three years on an investment of Rs.9000, what is the amount invested at 6 %?

• A. 3000
• B. 6000
• C. 4000
• D. 4500

Answer 1

The Correct Option is B

To solve this problem, we need to determine how much of the Rs.9000 was invested at 6% interest. Let's denote the amount invested in Bank A (at 6% interest) as Rs.x and in Bank B (at 8% interest) as Rs.(9000 - x).

We know the simple interest (SI) formula is given by:

SI = (Principal × Rate × Time) / 100

According to the problem, the total interest earned from both banks in 3 years is Rs.1800. Thus, we can set up the following equation:

The interest from Bank A: SI_A = (x × 6 × 3) / 100 = 0.18x

The interest from Bank B: SI_B = ((9000 - x) × 8 × 3) / 100 = 0.24(9000 - x)

The total interest is the sum of these two interests:

0.18x + 0.24(9000 - x) = 1800

Expanding and simplifying:

0.18x + 2160 - 0.24x = 1800

-0.06x + 2160 = 1800

Subtract 2160 from both sides to isolate terms involving x:

-0.06x = 1800 - 2160

-0.06x = -360

Dividing both sides by -0.06 gives:

x = 6000

Thus, the amount invested at 6% is Rs.6000.