Question

Difficulty: HardRatio and Proportion Word Problems

An artisan chocolate factory produces a signature dark chocolate blend using cocoa mass, cocoa butter, and cane sugar in the initial ratio of 2:3:42 : 3 : 4 by weight, respectively. To modify the flavor profile for a new batch, the master chocolatier adds 1010 kilograms of cocoa mass and 2020 kilograms of cocoa butter to the mix, while removing 55 kilograms of cane sugar. As a result, the ratio of cocoa mass to cocoa butter in the modified mixture becomes 4:74 : 7. What was the total weight, in kilograms, of the initial dark chocolate blend?

  1. A
    2525
  2. B
    3535
  3. 4545Answer
  4. D
    6060
  5. E
    7070

Answer

The total weight of the initial dark chocolate blend was 4545 kilograms.
By setting the initial weights of cocoa mass, cocoa butter, and cane sugar as 2x2x, 3x3x, and 4x4x, the initial total weight is 9x9x. The modified weights for cocoa mass and cocoa butter are 2x+102x + 10 and 3x+203x + 20, respectively. Equating their ratio to 47\frac{4}{7} gives 2x+103x+20=47\frac{2x + 10}{3x + 20} = \frac{4}{7}, which simplifies to 14x+70=12x+8014x + 70 = 12x + 80, so 2x=102x = 10 and x=5x = 5. Substituting x=5x = 5 into the total weight expression 9x9x yields 9(5)=459(5) = 45 kilograms.

Step-by-Step Solution

1
Define initial ingredient weights using a multiplier variable.
Cocoa mass = 2x2x, Cocoa butter = 3x3x, Cane sugar = 4x4x. Total initial weight = 2x+3x+4x=9x2x + 3x + 4x = 9x.
Expressing quantities in terms of a common ratio multiplier xx enables setting up algebraic equations after alterations.
2
Express the modified weights of cocoa mass and cocoa butter.
New cocoa mass = 2x+102x + 10; New cocoa butter = 3x+203x + 20.
The problem states 1010 kg of cocoa mass and 2020 kg of cocoa butter were added.
3
Set up the proportion equation using the new ratio of cocoa mass to cocoa butter.
2x+103x+20=47\frac{2x + 10}{3x + 20} = \frac{4}{7}
The modified ratio of cocoa mass to cocoa butter is given as 4:74 : 7.
4
Cross-multiply and solve for xx.
7(2x+10)=4(3x+20)    14x+70=12x+80    2x=10    x=57(2x + 10) = 4(3x + 20) \implies 14x + 70 = 12x + 80 \implies 2x = 10 \implies x = 5.
Solving the linear equation determines the common ratio multiplier value.
5
Calculate the initial total weight of the blend.
Initial total weight = 9x=9(5)=459x = 9(5) = 45 kg.
Multiplying the sum of all initial ratio parts by the multiplier gives the requested initial total weight.

Key Concept

Ratio setup and algebraic scaling in multi-part word problems with changing quantities
Estimated Time:2m 0s
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