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Finding the Fourth Proportional to 686.50, 1,029.72 and 339.72

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Solution

The fourth proportional to 686.50, 1,029.72 and 339.72 is: 509.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.50 : 1,029.72 = 339.72 : x
  2. Step 2: Convert to fraction form
    686.50/1,029.72 = 339.72/x
  3. Step 3: Cross multiply
    686.50x = 1,029.72 × 339.72
  4. Step 4: Simplify right side
    686.50x = 349,816.48
  5. Step 5: Solve for x
    x = 349,816.48/686.50
  6. Step 6: Final answer
    x = 509.57

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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.