Question

The value of a mobile depreciated by 5% per year during the first two years and 10% per year during the third year. Express the total depreciation of the value of the mobile in percent during the three years.

Answer 1

Let the value of mobile in the begging be Rs.100.
For 1^st year, depreciation = 5% of Rs.100

= `(5)/(100) xx 100`
= Rs.5
Value of machine for second year
= Rs.100 - Rs.5
= Rs.95
For 2^nd year, depreciation = 5% of Rs.95

= `(5)/(100) xx 95`
=Rs.4.75
Value of machine for third year 
= Rs.95 - Rs.4.75
= Rs.90.25
For 3^rd year, depreciation = 10% of Rs.90.25

= `(10)/(100) xx 90.25`
 =Rs.9.025
Value of machine at the end of third year
= Rs.90.25 - Rs.9.025
= Rs.81.225
Net depreciation
= Rs.100 - Rs.81.225
= Rs.18.775 or 18.775%.