Question

Difficulty: Very hardFinancial Mathematics (Interest, Profit, Loss, and Depreciation)

A trader bought a quantity of palm oil. He sold 13\frac{1}{3} of the total quantity at a profit of 20%20\%, 12\frac{1}{2} of the remaining palm oil at a loss of 10%10\%, and the rest of the palm oil at a profit of x%x\%. If his overall profit on the entire transaction was 15%15\%, what is the value of xx?

Answer: 35 %

Answer

The value of xx is 3535.
The palm oil is divided into three equal portions of 13\frac{1}{3} each. The first portion contributes 203%\frac{20}{3}\% profit, the second portion contributes a loss of 103%-\frac{10}{3}\%, and the final portion contributes x3%\frac{x}{3}\% profit. Summing these contributions yields 10+x3%\frac{10 + x}{3}\%. Equating this to the target overall profit of 15%15\% gives 10+x=4510 + x = 45, which solves to x=35x = 35.

Step-by-Step Solution

1
Determine the fractional portion of palm oil sold at each stage.
First portion = 13\frac{1}{3}. Remaining after first sale = 113=231 - \frac{1}{3} = \frac{2}{3}. Second portion = 12×23=13\frac{1}{2} \times \frac{2}{3} = \frac{1}{3}. Final portion = 1(13+13)=131 - \left(\frac{1}{3} + \frac{1}{3}\right) = \frac{1}{3}.
Finding the exact fraction of the total quantity sold at each step is necessary to weight their respective profit/loss rates correctly.
2
Formulate the net percentage profit equation.
\text{Net Profit } \% = \left(\frac{1}{3} \times 20\%\right) + \left(\frac{1}{3} \times (-10\%)\right) + \left(\frac{1}{3} \times x\%\right) = \frac{20 - 10 + x}{3}\% = \frac{10 + x}{3}\%
The overall profit percentage is the sum of individual fractional contributions, treating loss as a negative percentage.
3
Set the net profit equal to 15%15\% and solve for xx.
\frac{10 + x}{3} = 15 \implies 10 + x = 45 \implies x = 35
Solving this linear equation gives the required profit percentage for the final portion.

Key Concept

Weighted Average Profit and Loss across fractional components of an asset
Estimated Time:2m 0s
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