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Finding the Fourth Proportional to 426.81, 639.75 and 392.21

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Solution

The fourth proportional to 426.81, 639.75 and 392.21 is: 587.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.81 : 639.75 = 392.21 : x
  2. Step 2: Convert to fraction form
    426.81/639.75 = 392.21/x
  3. Step 3: Cross multiply
    426.81x = 639.75 × 392.21
  4. Step 4: Simplify right side
    426.81x = 250,918.41
  5. Step 5: Solve for x
    x = 250,918.41/426.81
  6. Step 6: Final answer
    x = 587.89

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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.