∴ Amount of Depreciation: 2015 = Rs.2,000
2016 = Rs.1,800
2017 = Rs. 1,620 

Amount of Depreciation = \({Total\ cost - Scrap\ value\over Estimated\ life}\)
\(={25,000-1,000\over 10}={24,000\over 10}\)
= Rs.11,200
Rate of Depreciation = \({Amount\ of\ Depreciation\over Original\ Cost}\times100\)
\(={11,200\over 60,000}\times100=18.67\%\)

Purchase price of plant = 4000
Erection charges = 2,000
Odginal cost = Ptuchase price + Installation charges
(i.e 40,000) + 2,000 =42000)
Effective life of the plant = 5 years
Estimated scrap value = Nil
\(\text { Amount of Depreciaion }=\frac{\text { Original cost - Estimated scrap value }}{\text { Estimated useful life of the asset in years }}\) 
= \(\frac{42000-0}{5 \text { years }}\) 
= Rs.8,400

(i) Under this method, the amount spent on the purchase of an asset is regarded as an investment. As such, the interest at a certain rate is calculated on the opening balance of the asset account each year and debited to the asset account.
(ii) The amount of depreciation written off is ascertained by- referring to the annuity table. Annual depreciation is uniform throughout the working life of the asset.

The following are the different methods of providing depreciation:
(i) Straight line method or Fixed instalment method or Original cost method
(ii) Written down value method or Diminishing balance method
(iii) Sum of years of digits method
(iv) Machine hour rate method
(v) Depletion method
(vi) Annuity method
(vii) Revaluation method
(viii) Sinking fund method
(ix) Insurance policy method