ML Aggarwal CBSE Solutions Class 8 Math 7th Chapter Compound Interest Exercise 7.3
(6) V0 = Present value = 16000
V = Value after 2 years = 14440
N = 2 years
R =?
V = V0 [1- r/100]r
Or, 14440 = 16000 (1 – r/100)2
Or, 14440/16000 = (1 – r/100)2
Or, (38/40)2 = (1- r/100)2
Or, 38/40 = 1 – r/100
Or, r/100 = 1 – 38/40 = 40–38/40 = 2/40
Or, r = 2X10/4 = 5% (Ans)
(7) V0 = 80000
V = 92610
N = 3 years
V = V0 [1+ r/100]n
Or, 92610 = 80000 [1+ r/100]3
Or, 9261/8000 = (1+ r/100)3
Or, (21/20)3 = (1+ r/100)3
Or, 21/20 = 1+ r/100
Or, 21/20 – 1 = r/100
Or, 21-20/20 = r/100
Or, 1 X 5 = r
Or, r = 5% (Ans)