Question

the cost of a new washing machine is rs. 22000. its value depreciate every year. if the depriciated value of washing machine after 2 year is rs. 14080, find the rate of deprication.

Answer 1

Please find below the solution to the asked query:

Given : Compound interest on a sum of Rs 8000 at a certain rate of interest compounded annually for 2 years is Rs 6480

Let rate of depreciation = r %

We know formula for compound interest :

Amount = P(1 +r100)t   , Here P  = 8000 , t  =  2 , Compound interest = 6480 , So

8000 (1 + r100)2 = 6480⇒(1 + r100)2 = 64808000 ⇒(1 + r100)2 = 81100 ⇒(1 + r100)2 = 92102 ⇒(1 + r100)2 = (910 )2⇒1 + r100= 910 ⇒r100= 910  − 1⇒r100= 9 − 1010 ⇒r100= − 110 ⇒r= − 110 ×100⇒r= − 10
Here negative sign shows that is a rate of depreciation .

Therefore,

Rate of depreciation = 10 %                                                                            ( Ans )

Hope this information will clear your doubts about Compound Interest .

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