Dinesh invested Rs. (P-500) at the rate of 27% per annum

Solution

Dinesh invested Rs. (P-500) at the rate of 27% per annum on simple interest and at the end of three years, he got Rs. 4860 as an interest. (P-500)x27%x3 = 4860 (P-500)x81% = 4860 (P-500) = 486000/81 (P-500) = 6000 P = 6000+500 P = 6500 Bhanu invested Rs. (P-100) on compound interest at the rate of ‘R’ % per annum compounded annually. Pankaj invested Rs. (P+300) on simple interest at the rate of (R-2) % per annum. If at the end of two years, the interest obtained by Bhanu is 368 more than the interest obtained by Pankaj. (P-100)[(1+(R/100)) ² - 1] = [(P+300)x(R-2)x2]/100 + 368 Put the value of ‘P’ in the above equation. (6500-100)[(1+(R/100)) ² -1] = [(6500+300)x(R-2)x2]/100 + 368 6400[(1+(R/100)) ² -1] = [6800x(R-2)x2]/100 + 368 After solving the above equation, we will get a quadratic equation which is given below. 64R ² -800R-9600 = 0 2R ² -25R-300 = 0 2R ² -(40-15)R-300 = 0 2R ² - 40R+15R-300 = 0 2R(R-20)+15(R-20) = 0 (R-20) (2R+15) = 0 R = 20, -(15/2) As we know that the negative value of ‘R’ is not possible. So the value of ‘R’ is 20 .