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A companyтАЩs profit decreased by 15% each year from 200000. What will be the profit after four years?
109290.25
108290.25
104401.25
116290.25
104401.25
Use the ratio method: 15% decrease means the profit becomes 85% or 17/20 of the previous year's value. Calculate 200000├Ч(17/20)4=200000├Ч(83521/160000)=1.25├Ч83521=104401.25.
Initial profit P = 200000, rate of decrease r = 15% per year, and time period n = 4 years.
A=P├Ч(1тИТ100rтАЛ)n
Use the ratio method: 15% decrease means the profit becomes 85% or 17/20 of the previous year's value. Calculate 200000├Ч(17/20)4=200000├Ч(83521/160000)=1.25├Ч83521=104401.25.
Many students mistake simple interest depreciation for compound depreciation; ensure you apply the exponent of 4 to the multiplier, not just multiplying by 4.
Define variables
Identify the initial principal P=200000, the annual decrease rate r=15%, and the duration n=4.
P=200000,r=15%,n=4
Set up the compound depreciation formula
Since the profit decreases successively each year, we use the formula for exponential decay.
A=200000├Ч(1тИТ10015тАЛ)4
Simplify the base value
Convert the percentage to a fraction: 1тИТ0.15=0.85 or 85/100=17/20.
A=200000├Ч(2017тАЛ)4
Calculate the final result
Evaluate the power: (17/20)4=83521/160000. Multiplying this by 200000 gives 200000├Ч0.52200625=104401.25.
A=200000├Ч16000083521тАЛ=104401.25
C is correct because calculating the successive decrease of 15% over 4 years on 200000 results in 104401.25.
This same logic applies to calculating the depreciated value of fixed assets (like machinery) in Accounting or the population decline of bacteria in Biology.