Multiple choice

Compound interest on a sum of money for 2 years, at rate of 20% p.a., is Rs. 660. Calculate SI on the same sum for double the time and at half the rate p.a.

  1. Rs. 650

  2. Rs. 700

  3. Rs. 1500

  4. Rs. 600

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

CI = P((1+r/100)^n - 1). 660 = P((1.2)^2 - 1) = P(0.44). P = 660/0.44 = 1500. SI = (P * R * T)/100. New T = 4, new R = 10. SI = (1500 * 10 * 4)/100 = 600.

AI explanation

Let the sum be P, so the compound interest formula for two years gives 660 equal to P multiplied by 44 divided by 100, which solves to a principal of Rs. 1500. The simple interest is calculated for double the time (4 years) at half the rate (10%), so simple interest equals 1500 multiplied by 10 multiplied by 4 divided by 100. The resulting simple interest is Rs. 600.

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