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Finding the Fourth Proportional to 426.48, 639.78 and 137.92

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Solution

The fourth proportional to 426.48, 639.78 and 137.92 is: 206.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.48 : 639.78 = 137.92 : x
  2. Step 2: Convert to fraction form
    426.48/639.78 = 137.92/x
  3. Step 3: Cross multiply
    426.48x = 639.78 × 137.92
  4. Step 4: Simplify right side
    426.48x = 88,238.46
  5. Step 5: Solve for x
    x = 88,238.46/426.48
  6. Step 6: Final answer
    x = 206.90

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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.