Multiple choice

What was the total compound interest on a sum after three years? Statement I: The interest after one year was Rs.100 and the sum was Rs.1000. Statement II: The difference between simple and compound interest on a sum of Rs.1000 at the end of two years was Rs.10.

  1. If the data in statement I alone are sufficient to answer the question, while the data in statement II alone are not sufficient to answer the question

  2. If the data in statement II alone are sufficient to answer the question, while the data in statement I alone are not sufficient to answer the question.

  3. If the data either in statement I alone or in statement II alone are sufficient to answer the question.

  4. If the data even in both the statements I and II together are not sufficient to answer the question.

  5. If the data in both the statements I and II together are necessary to answer the question.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Statement I: Principal = 1000, CI after 1 year = 100 at rate r. So 1000(1 + r) - 1000 = 100, giving 1000r = 100, so r = 10%. CI for 3 years at 10%: 1000[(1.1)^3 - 1] = 1000(1.331 - 1) = 331. Sufficient alone. Statement II: For principal 1000, SI - CI after 2 years = 10. SI = 1000 * 2r = 2000r, CI = 1000[(1+r)^2 - 1] = 1000(2r + r^2) = 2000r + 1000r^2. Difference = 1000r^2 = 10, so r^2 = 0.01, r = 10%. CI for 3 years: 1000[(1.1)^3 - 1] = 331. Also sufficient alone. Either statement gives the answer. Option C is correct.

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