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Finding the Third Proportional to 391.91 and 520.05

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Solution

The third proportional to 391.91 and 520.05 is: 690.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.91 : 520.05 = 520.05 : x
  2. Step 2: Convert to fraction form
    391.91/520.05 = 520.05/x
  3. Step 3: Cross multiply
    391.91x = 520.05 × 520.05
  4. Step 4: Simplify right side
    391.91x = 270,455.35
  5. Step 5: Solve for x
    x = 270,455.35/391.91
  6. Step 6: Final answer
    x = 690.10

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Why These Related Problems?

These problems maintain the same ratio (1.33) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.