The of a washing machine depreciated by Rs.720 during the second year and by Rs.648 during the third year.Calculate: (i)the rate of depreciation per annum. (ii)the original cost of the machine. (iii)the value of the machine at the end of third year.

(i) Rate of depreciation = (720 - 648/720)*(100) = (72/720)*100 = 10%

(ii) Let the original cost be x. 

Rate of depreciation 10%

Then, x - (10x/100) = 720

=>(100x - 10x)/100 = 720

=>90x/100 = 720

=>x = 720 * 10/9 = Rs 800

(iii) Value at the end of third year = 648 - (10* 648/100) = 648 - 64.8 = Rs 583.2