Multiple choice

If any amount doubles itself in 5 years at the interest rate compounded annually then in how many years will it become eight times ? यदि कोई धनराशि चक्रवृद्धि ब्याज पर 5 वर्षों में दोगुनी हो जाती है, तो वह धनराशि कितने वर्षों में आठ गुनी हो जायेगी?

  1. 18 years 18 वर्ष

  2. 21 years 21 वर्ष

  3. 24 years 24 वर्ष

  4. 15 years 15 वर्ष

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

If amount doubles in 5 years, then 2^n = 8 gives n = 3. So 3 doubling periods needed. Total time = 3 × 5 = 15 years for amount to become 8 times itself (since 2³ = 8).

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