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Finding the Fourth Proportional to 686.18, 946.86 and 391.40

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Solution

The fourth proportional to 686.18, 946.86 and 391.40 is: 540.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.18 : 946.86 = 391.40 : x
  2. Step 2: Convert to fraction form
    686.18/946.86 = 391.40/x
  3. Step 3: Cross multiply
    686.18x = 946.86 × 391.40
  4. Step 4: Simplify right side
    686.18x = 370,601.00
  5. Step 5: Solve for x
    x = 370,601.00/686.18
  6. Step 6: Final answer
    x = 540.09

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1.5x scale

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.