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Finding the Fourth Proportional to 426.39, 639.63 and 318.86

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Solution

The fourth proportional to 426.39, 639.63 and 318.86 is: 478.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.39 : 639.63 = 318.86 : x
  2. Step 2: Convert to fraction form
    426.39/639.63 = 318.86/x
  3. Step 3: Cross multiply
    426.39x = 639.63 × 318.86
  4. Step 4: Simplify right side
    426.39x = 203,950.83
  5. Step 5: Solve for x
    x = 203,950.83/426.39
  6. Step 6: Final answer
    x = 478.33

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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.