Multiple choice

Ragu invested Rs.72000 in two different parts one at 20% SI and another one at 20% CI (Compounded annually). What is the difference between the amount invested in SI and CI, if he received total interest at the end of two years is Rs.30480?

  1. 10000

  2. 15000

  3. 12000

  4. 8000

  5. 16000
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let x be the amount at 20% SI and (72000 - x) be at 20% CI. SI = x * 0.2 * 2 = 0.4x. CI = (72000 - x) * ((1.2)^2 - 1) = (72000 - x) * 0.44. Total interest = 0.4x + 0.44(72000 - x) = 30480. Solving gives 0.04x = 31680 - 30480 = 1200, x = 30000. The other part is 42000. The difference is 12000.

AI explanation

Let the amount invested at simple interest be y, so the amount at compound interest is 72000 minus y. The simple interest for two years is 0.4y, and the compound interest for two years is 0.44 times (72000 minus y). Their sum equals the total interest of 30480, giving the equation 0.4y plus 31680 minus 0.44y equals 30480. Solving this, 0.04y equals 1200, so y equals 30000. The difference between the two investments is 42000 minus 30000, which is 12000.

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