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Finding the Fourth Proportional to 687.12, 1,029.34 and 425.90

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Solution

The fourth proportional to 687.12, 1,029.34 and 425.90 is: 638.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.12 : 1,029.34 = 425.90 : x
  2. Step 2: Convert to fraction form
    687.12/1,029.34 = 425.90/x
  3. Step 3: Cross multiply
    687.12x = 1,029.34 × 425.90
  4. Step 4: Simplify right side
    687.12x = 438,395.91
  5. Step 5: Solve for x
    x = 438,395.91/687.12
  6. Step 6: Final answer
    x = 638.02

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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.