A sum of money at compound interest amounts to thrice itself in 3 years. In how many years will it be 9 times itself? एक धनराशि, चक्रवृद्धि ब्याज पर 3 वर्षों में तीन गुनी हो जाती है। तदनुसार, वह अपनी मूल राशि की 9 गुनी कितने वर्षों में हो जाएगी?

In compound interest, if an amount becomes n times in t years, it becomes n^k times in k×t years (geometric progression). Here, amount becomes 3 times in 3 years. To become 9 times (which is 3²), it takes 2×3 = 6 years. Option A (9) incorrectly uses linear progression, while option B (27) would give 27 times (3³), not 9 times.