Soru

Zorluk: OrtaPercent Change and Interest

A commercial real estate developer purchases a building. In the first year after purchase, the value of the building increases by 40%40\%. In the second year, the value decreases by 25%25\% from its first-year value. In the third year, the value increases by 20%20\% from its second-year value. If the value of the building at the end of the third year is $630,000\$630,000, what was the original purchase price of the building?

  1. A
    $375,000\$375,000
  2. B
    $378,000\$378,000
  3. C
    $450,000\$450,000
  4. $500,000\$500,000Cevap
  5. E
    $525,000\$525,000

Cevap

The original purchase price of the building was $500,000\$500,000.
To find the original price, express each sequential percent change as a multiplier applied to the preceding value. A 40%40\% increase corresponds to a factor of 1.401.40, a 25%25\% decrease corresponds to a factor of 0.750.75, and a 20%20\% increase corresponds to a factor of 1.201.20. Combining these gives a overall multiplier of 1.40×0.75×1.20=1.261.40 \times 0.75 \times 1.20 = 1.26. Setting 1.26×P=$630,0001.26 \times P = \$630,000 yields P=$500,000P = \$500,000.

Adım Adım Çözüm

1
Express each annual percentage change as a multiplier factor.
Year 1 increase of 40%1+0.40=1.40=7540\% \rightarrow 1 + 0.40 = 1.40 = \frac{7}{5}. Year 2 decrease of 25%10.25=0.75=3425\% \rightarrow 1 - 0.25 = 0.75 = \frac{3}{4}. Year 3 increase of 20%1+0.20=1.20=6520\% \rightarrow 1 + 0.20 = 1.20 = \frac{6}{5}.
Successive percentage changes compound sequentially on the updated intermediate values.
2
Calculate the cumulative multiplier over the three-year period.
\text{Overall Multiplier} = 1.40 \times 0.75 \times 1.20 = \frac{7}{5} \times \frac{3}{4} \times \frac{6}{5} = \frac{126}{100} = 1.26.
Multiplying individual year multipliers yields the net scale factor from the initial price to the final value.
3
Set up the linear equation for the initial price PP and solve.
1.26 \times P = 630,000 \implies P = \frac{630,000}{1.26} = 500,000.
Dividing the final valuation by the overall multiplier determines the original purchase price.

Anahtar Kavram

Successive Percent Change
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