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Finding the Fourth Proportional to 426.96, 639.72 and 405

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Solution

The fourth proportional to 426.96, 639.72 and 405 is: 606.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.96 : 639.72 = 405 : x
  2. Step 2: Convert to fraction form
    426.96/639.72 = 405/x
  3. Step 3: Cross multiply
    426.96x = 639.72 × 405
  4. Step 4: Simplify right side
    426.96x = 259,086.60
  5. Step 5: Solve for x
    x = 259,086.60/426.96
  6. Step 6: Final answer
    x = 606.82

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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.