Question
Suresh earned an interest of Rs. 1032 on principal
amount of Rs. 3200 at some rate of compound interest in 2 years. How much more/less interest would he have earned on Rs. 3600 at the same rate of simple interest for the same duration?Solution
Let, rate of interest be βrβ% per annum So, 1032 = 3200 Γ {(1 + r/100)2 β 1} 129/400 = {(1 + r/100)2 β 1} 529/400 = (1 + r/100)2 (23/20)2 = (1 + r/100)2 23/20 = 1 + r/100 3/20 = r/100, r = 15 So, simple interest earned = 3600 Γ 0.15 Γ 2 = Rs. 1080 Required amount = 1080 β 1032 = Rs. 48
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