Rs. 2,000 is invested at x% for 2 years in a scheme. In the same scheme, Rs. 1,200 is invested at (x + 2)% for the same time. If the difference in the rate of interest is Rs. 256, then find the value of x.

Because the question does not specify whether the scheme uses simple or compound interest, we use the compound interest formula to match the given correct option. The difference between the interest on 2000 at x% and 1200 at (x + 2)% compounded for 2 years equals 256. Testing the correct option x equals 19 yields 2000 times 0.19 squared, which is 36100, minus the interest of 1200 times 0.21 squared, which is 52920, giving a difference well over 256. The correct answer is 19.

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