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Finding the Fourth Proportional to 686.13, 946.86 and 391.40

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Solution

The fourth proportional to 686.13, 946.86 and 391.40 is: 540.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.13 : 946.86 = 391.40 : x
  2. Step 2: Convert to fraction form
    686.13/946.86 = 391.40/x
  3. Step 3: Cross multiply
    686.13x = 946.86 × 391.40
  4. Step 4: Simplify right side
    686.13x = 370,596.27
  5. Step 5: Solve for x
    x = 370,596.27/686.13
  6. Step 6: Final answer
    x = 540.13

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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.