A manufacturer recons that the value of a machine which costs him Rs. 125000 will depreciate each year by 20%. Find the estimated value of the machine at the end of 5 years.
Short- cut method
Value of the machine after 5 years=Rs.{(1−20100)5}=Rs.{125000×(45)5}=Rs.(125000×10243125)=Rs.40960.Hence, the vale of the machine after 5 year is Rs. 40960
Alternative method
Intial value of the machine = Rs. 125000Value fo the machine after 1 year = 80%ofRs.125000=Rs.(125000×80100)=Rs.80000.Thus, the yearwise values of the machine areRs.125000,Rs.100000,Rs.80000,⋯here,100000125000=45,80000100000=45,etc.thus these amounts from a GP with a = 125000 andr=45.Value after 5 years = 6th term=T6=ar(6−1)=ar5=Rs.{125000×(45)5}=Rs.(125000×10243125)=Rs.40960.