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Finding the Fourth Proportional to 439.20, 657.45 and 390.60

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Solution

The fourth proportional to 439.20, 657.45 and 390.60 is: 584.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    439.20 : 657.45 = 390.60 : x
  2. Step 2: Convert to fraction form
    439.20/657.45 = 390.60/x
  3. Step 3: Cross multiply
    439.20x = 657.45 × 390.60
  4. Step 4: Simplify right side
    439.20x = 256,799.97
  5. Step 5: Solve for x
    x = 256,799.97/439.20
  6. Step 6: Final answer
    x = 584.70

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.