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Zorluk: ZorRatios, Rates, and Proportions

A commercial bakery mixes three types of flour—whole wheat, rye, and oat—to create a specialty bread blend. Initially, the ratio of whole wheat flour to rye flour to oat flour by weight is 5:3:25:3:2. The baker then adds 12 pounds of oat flour and 6 pounds of rye flour to the batch while leaving the amount of whole wheat flour unchanged. As a result, the ratio of whole wheat flour to oat flour in the new mixture becomes 1:11:1. What was the total weight, in pounds, of the initial flour mixture before any additional flour was added?

  1. A
    20
  2. B
    32
  3. 40Cevap
  4. D
    58
  5. E
    60

Cevap

The total weight of the initial flour mixture was 40 pounds.
Representing the initial amounts of whole wheat, rye, and oat flour as 5x5x, 3x3x, and 2x2x establishes that the initial total weight is 10x10x. Adding 12 pounds to the oat flour makes the new oat weight 2x+122x + 12. Because the new ratio of whole wheat to oat is 1:11:1, we set 5x=2x+125x = 2x + 12, which yields x=4x = 4. Multiplying the multiplier x=4x = 4 by the total number of parts (1010) gives the original total weight of 40 pounds.

Adım Adım Çözüm

1
Express the initial weights using a common multiplier xx.
Whole Wheat = 5x5x, Rye = 3x3x, Oat = 2x2x. The total initial weight is 5x+3x+2x=10x5x + 3x + 2x = 10x.
An extended ratio of 5:3:25:3:2 means each component is a multiple of a shared constant xx.
2
Set up an equation based on the new ratio of whole wheat to oat flour.
Whole Wheat = 5x5x, New Oat = 2x+122x + 12. Since the ratio is 1:11:1, 5x=2x+125x = 2x + 12.
Adding 12 pounds of oat flour changes the oat amount to 2x+122x + 12, and a 1:11:1 ratio means the two amounts are equal.
3
Solve for the multiplier xx.
3x=12x=43x = 12 \Rightarrow x = 4.
Subtract 2x2x from both sides and divide by 3.
4
Calculate the total initial weight.
Total initial weight = 10x=10(4)=4010x = 10(4) = 40 pounds.
Substitute x=4x = 4 back into the total initial expression 10x10x.

Anahtar Kavram

Solving multi-part ratio change problems by expressing quantities in terms of a common variable.
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