Multiple choice

The difference between the compound interest and Simple interest on a certain sum at certain interest is Rs. 64.If the compound interest for 2 years is rs. 704.Then rate % and principal should be : A. 20% , 800 rs B. 20% ,1600 rs C.10% , 2400 rs D.20% , 3200 rs E. None of these

  1. E

  2. A

  3. C

  4. B

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

For 2 years, CI - SI = P * (r/100)^2. Given CI - SI = 64 and CI = 704, SI = 704 - 64 = 640. Since SI for 2 years is 640, SI for 1 year is 320. Using P * r / 100 = 320 and P * (r/100)^2 = 64, we divide the equations: r/100 = 64/320 = 0.2, so r = 20%. Then P * 0.2 = 320, so P = 1600.

AI explanation

The difference between compound interest and simple interest for 2 years is given by P times R squared divided by 10000, so 64 equals P times R squared divided by 10000. The compound interest formula for 2 years can also be used with the total interest of 704, and checking the given options against both conditions reveals that 20 percent and 1600 rs satisfy both equations perfectly. Testing option B, the simple interest is 640, and the compound interest is 704, creating a difference of exactly 64 rs. The correct rate and principal are 20 percent and Rs. 1600.

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