Multiple choice

What sum will amount to 4000 Rs. after 3 years and Rs.10000 after 6 years at compound interest? कौन सी धनराशि चक्रवृद्धि ब्याज पर तीन वर्ष बाद 4000 रु तथा छः वर्ष बाद 10000 रु हो जायेगी ?

  1. Rs.1600

  2. Rs.1500

  3. Rs.1800

  4. Rs.1200
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A Correct answer
Explanation

Let P be principal and r be rate. Then P(1+r)^3 = 4000 and P(1+r)^6 = 10000. Dividing: (1+r)^3 = 10000/4000 = 2.5. Substituting back: P × 2.5 = 4000, so P = 1600. This compound interest problem uses the property that the amount after different time periods can reveal both principal and rate.

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