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Finding the Fourth Proportional to 426.90, 640.45 and 138.54

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Solution

The fourth proportional to 426.90, 640.45 and 138.54 is: 207.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.90 : 640.45 = 138.54 : x
  2. Step 2: Convert to fraction form
    426.90/640.45 = 138.54/x
  3. Step 3: Cross multiply
    426.90x = 640.45 × 138.54
  4. Step 4: Simplify right side
    426.90x = 88,727.25
  5. Step 5: Solve for x
    x = 88,727.25/426.90
  6. Step 6: Final answer
    x = 207.84

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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.