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Finding the Third Proportional to 291.56 and 640.69

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Solution

The third proportional to 291.56 and 640.69 is: 1,407.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    291.56 : 640.69 = 640.69 : x
  2. Step 2: Convert to fraction form
    291.56/640.69 = 640.69/x
  3. Step 3: Cross multiply
    291.56x = 640.69 × 640.69
  4. Step 4: Simplify right side
    291.56x = 410,480.47
  5. Step 5: Solve for x
    x = 410,480.47/291.56
  6. Step 6: Final answer
    x = 1,407.86

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Why These Related Problems?

These problems maintain the same ratio (2.20) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.