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Finding the Fourth Proportional to 425.39, 638.69 and 390.15

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Solution

The fourth proportional to 425.39, 638.69 and 390.15 is: 585.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    425.39 : 638.69 = 390.15 : x
  2. Step 2: Convert to fraction form
    425.39/638.69 = 390.15/x
  3. Step 3: Cross multiply
    425.39x = 638.69 × 390.15
  4. Step 4: Simplify right side
    425.39x = 249,182.95
  5. Step 5: Solve for x
    x = 249,182.95/425.39
  6. Step 6: Final answer
    x = 585.78

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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.