Question

Difficulty: MediumPercentages, Percent Change, and Interest

At a logistics company, fuel expenditure accounted for 40%40\% of total operational costs in Year 1, while maintenance expenditure accounted for the remaining 60%60\%. In Year 2, fuel expenditure increased by 25%25\%, and maintenance expenditure decreased by 15%15\%. If there were no other operational costs in either year, by what percentage did the total operational cost change from Year 1 to Year 2?

  1. An increase of 1%1\%Answer
  2. B
    An increase of 5%5\%
  3. C
    An increase of 9%9\%
  4. D
    An increase of 10%10\%
  5. E
    A decrease of 1%1\%

Answer

An increase of 1%1\%
The total operational cost increases by 1%1\% because fuel cost increases by 0.40×25%=+10%0.40 \times 25\% = +10\% of the total cost, while maintenance cost decreases by 0.60×15%=9%0.60 \times 15\% = -9\% of the total cost, yielding a net change of +10%9%=+1%+10\% - 9\% = +1\%.

Step-by-Step Solution

1
Assign an arbitrary base value or variable for Year 1 total cost
Let the total operational cost in Year 1 be C=100C = 100. Thus, fuel expenditure is 4040 and maintenance expenditure is 6060.
Choosing a concrete baseline value makes multi-step percentage change calculations clear and straightforward.
2
Calculate Year 2 cost for each component
Year 2 fuel cost =40×(1+0.25)=50= 40 \times (1 + 0.25) = 50. Year 2 maintenance cost =60×(10.15)=51= 60 \times (1 - 0.15) = 51.
Apply the individual percentage increase (+25%+25\%) and decrease (15%-15\%) to the respective Year 1 component values.
3
Sum the Year 2 component costs and compute total percentage change
Total Year 2 cost =50+51=101= 50 + 51 = 101. Percent change =101100100×100%=+1%= \frac{101 - 100}{100} \times 100\% = +1\%.
Compare the new total operational cost to the original baseline cost to determine net percentage change.

Key Concept

Weighted Percentage Change
Estimated Time:1m 30s
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