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Finding the Fourth Proportional to 686.10, 946.43 and 391.31

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Solution

The fourth proportional to 686.10, 946.43 and 391.31 is: 539.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.10 : 946.43 = 391.31 : x
  2. Step 2: Convert to fraction form
    686.10/946.43 = 391.31/x
  3. Step 3: Cross multiply
    686.10x = 946.43 × 391.31
  4. Step 4: Simplify right side
    686.10x = 370,347.93
  5. Step 5: Solve for x
    x = 370,347.93/686.10
  6. Step 6: Final answer
    x = 539.79

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.