On a certain sum of money the compound interest for 2 years is Rs. 28215 and the simple interest for the same period of time is Rs. 27000. The rate of interest per annum is - किसी निश्चित धनराशि पर दो वर्षों के लिए चक्रवृद्धि ब्याज 28215 रू. तथा समान समयावधि के लिए साधारण ब्याज 27000 रू. है तो वार्षिक ब्याज की दर है-
C
Correct answer
Explanation
For 2 years at rate r%, simple interest SI = P × r × 2 / 100. Compound interest CI = P(1 + r/100)² - P = P[(1 + r/100)² - 1]. Given CI - SI = 28215 - 27000 = 1215. This difference equals P × r² / 10000 (the extra interest from compounding). Also SI = 2Pr/100 = 27000. From SI, P = 27000 × 100 / (2r) = 1350000/r. Substituting in CI - SI: (1350000/r) × r² / 10000 = 1215, giving 135r/10000 = 1215/1000, so r = 9%. The difference between CI and SI for 2 years is always P(r/100)².