Question

Rs. 1200 was invested at 12% per annum simple interest and a certain sum of money invested at 10% per annum simple interest. If the sum of the interest after 6 years is Rs. 1280, then what is the latter sum of money?
1. Rs. 693.33
2. Rs. 348.66
3. Rs. 687.33
4. Rs. 653.33

Answer 1

Correct Answer - Option 1 : Rs. 693.33

Given:

Principal for 1^st investment = Rs. 1200

Sum of interest received after 6 years = Rs. 1280

Rate R1 = 12%

Rate R2 = 10%

Calculation:

For 1^st investment:

Principal = 1200

Rate = 12%

Time = 6 years

∴ SI = (1200 × 12 × 6)/100

⇒ 144 × 6

⇒ 864

∴ SI on 2^nd investment = 1280 - 864

⇒ 416

Let the principal of the second investment be x

Time = 6 years

Rate = 10

∴ 416 = x × 10 × 6/100

⇒ 41600 = 60x

⇒ x = 41600/60

⇒ x = 693.33

∴ the latter sum of money is Rs. 693.33.