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Mathematics

The value of a machine depreciates every year at a constant rate. If the values of the machine in 2006 and 2008 are ₹ 25,000 and ₹ 19,360 respectively, then the annual rate of depreciation is:

  1. 8%

  2. 10%

  3. 12%

  4. 14%

Compound Interest

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Answer

Given,

Initial value (P) = ₹ 25,000

Depreciated value (A) = ₹ 19,360

n = 2 years

Let rate of depreciation be R.

Value of machine after n years = [V×(1R100)n]\Big[V \times \Big(1 - \dfrac{R}{100}\Big)^n \Big]

19360=25000(1R100)219360=25000(1R100)21936025000=(1R100)2484625=(1R100)2(2225)2=(1R100)22225=1R100R100=12225R100=252225R100=325R=3×10025R=3×4R=12%\Rightarrow 19360 = 25000 \Big(1 - \dfrac{R}{100}\Big)^{2} \\[1em] \Rightarrow 19360 = 25000 \Big(1 - \dfrac{R}{100}\Big)^2 \\[1em] \Rightarrow \dfrac{19360}{25000} = \Big(1 - \dfrac{R}{100}\Big)^2 \\[1em] \Rightarrow \dfrac{484}{625} = \Big(1 - \dfrac{R}{100}\Big)^2 \\[1em] \Rightarrow \Big(\dfrac{22}{25}\Big)^2 = \Big(1 - \dfrac{R}{100}\Big)^2 \\[1em] \Rightarrow \dfrac{22}{25} = 1 - \dfrac{R}{100} \\[1em] \Rightarrow \dfrac{R}{100} = 1 - \dfrac{22}{25} \\[1em] \Rightarrow \dfrac{R}{100} = \dfrac{25 - 22}{25} \\[1em] \Rightarrow \dfrac{R}{100} = \dfrac{3}{25} \\[1em] \Rightarrow R = \dfrac{3 \times 100}{25} \\[1em] \Rightarrow R = 3 \times 4\\[1em] \Rightarrow R = 12\%

Hence, option 3 is correct option.

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