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Finding the Fourth Proportional to 487.20, 730.08 and 390.72

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Solution

The fourth proportional to 487.20, 730.08 and 390.72 is: 585.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    487.20 : 730.08 = 390.72 : x
  2. Step 2: Convert to fraction form
    487.20/730.08 = 390.72/x
  3. Step 3: Cross multiply
    487.20x = 730.08 × 390.72
  4. Step 4: Simplify right side
    487.20x = 285,256.86
  5. Step 5: Solve for x
    x = 285,256.86/487.20
  6. Step 6: Final answer
    x = 585.50

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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.