Steve has Rs. 12000/-, he invested some amount at 10% and rest at 12% simple interest. His income from these investment is Rs.1280/-. How much he invest at 10%?
amount invested at 10% -- x
amount invested at 12% ---- 12000 - x
.10x + .12(12000 - x) = 1280
easy to solve for x
To find out how much Steve invested at 10%, we can use the formula for simple interest:
Interest = Principal * Rate * Time
Let's assume Steve invested x amount at 10% and (12000 - x) amount at 12%.
For the investment at 10%:
Principal = x
Rate = 10% = 0.10
For the investment at 12%:
Principal = 12000 - x
Rate = 12% = 0.12
Now we can calculate the interest earned from each investment:
Interest from 10% investment = x * 0.10 * 1 (assuming the time is 1 year)
Interest from 12% investment = (12000 - x) * 0.12 * 1 (assuming the time is 1 year)
According to the given information, the sum of the interest from both investments is Rs. 1280:
x * 0.10 * 1 + (12000 - x) * 0.12 * 1 = 1280
Simplifying the equation:
0.10x + 0.12(12000 - x) = 1280
0.10x + 1440 - 0.12x = 1280
-0.02x = 1280 - 1440
-0.02x = -160
x = -160 / -0.02
x = 8000
Therefore, Steve invested Rs. 8000 at 10% interest.