Dear Sir, please solve this question The difference between the compound interest and the simple interest on Rs.42000 for 2 years is Rs.105 at the same rate of interest per annum. Find: 1. The rate of interest ? 2.The compound interest earned in the second year? Share with your friends Share 11 Manbar Singh answered this We have,Principal, P = Rs 42000Rate, R = ?Time, t = 2 years1.CI - SI = Rs 105We know that,CI = Amount - Principal = P1 +R100t - P = P1+R1002 - P = P1+R1002 - 1 = P1 + R210000 + 2R100 - 1 = PR210000 + 2R100SI = P × R × t100 = P × R × 2100 = 2PR100Now, CI - SI = 105⇒ PR210000 + 2R100 - 2PR100 = 105⇒ PR210000 + 2R100 -2R100 = 105⇒ PR210000 = 105⇒ 42000 × R210000 = 105⇒ 42R210 = 105⇒ R2 = 105042 = 25⇒ R = 5∴ Rate of interest is 5% per annum. 2.P = Rs 42000R = 5% p.an = 1 yrA1 = P1+R100n = 42000×1+51001 = 42000×2120 = Rs 44100Now, principal for second year, P2 = A1 =Rs 44100Rate, R = 5% p.an = 1 yrNow, A2 = P21+R100n = 44100×1+51001 = 44100×2120 = Rs 46305Now, Interest earned in second year = A2 - P2 = 46305 - 44100 = Rs 2205 9 View Full Answer Suryatapa Sarkar answered this {@_@} SI=42000.r.2/100 SI=840r CI=42(100+r)r/10 CI-SI=105 4200r+42r2-8400r=1050 now find r ,then put the value of r in CI for 2 yrs. 1
