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Finding the Fourth Proportional to 686.53, 1,028.78 and 408.59

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Solution

The fourth proportional to 686.53, 1,028.78 and 408.59 is: 612.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.53 : 1,028.78 = 408.59 : x
  2. Step 2: Convert to fraction form
    686.53/1,028.78 = 408.59/x
  3. Step 3: Cross multiply
    686.53x = 1,028.78 × 408.59
  4. Step 4: Simplify right side
    686.53x = 420,352.06
  5. Step 5: Solve for x
    x = 420,352.06/686.53
  6. Step 6: Final answer
    x = 612.29

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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.