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Finding the Fourth Proportional to 686.72, 1,028.40 and 397.28

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Solution

The fourth proportional to 686.72, 1,028.40 and 397.28 is: 594.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.72 : 1,028.40 = 397.28 : x
  2. Step 2: Convert to fraction form
    686.72/1,028.40 = 397.28/x
  3. Step 3: Cross multiply
    686.72x = 1,028.40 × 397.28
  4. Step 4: Simplify right side
    686.72x = 408,562.75
  5. Step 5: Solve for x
    x = 408,562.75/686.72
  6. Step 6: Final answer
    x = 594.95

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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.