A sofa of MRP 450 is available in Rs.90 cash down payment and 9 monthly equal installment of Rs.45 each. Find the rate of interest per annum.
Total interest = 90 + 45 x 9 – 540 = Rs. 45 45 = (360 + 315 + 270 + 225 + 180 +…. + 45) x R x 1/ (12 x 100) 45 = 1620 x R/1200 100 = 3R R = 100/3 %
