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Finding the Fourth Proportional to 939.05, 1,408.58 and 391.85

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Solution

The fourth proportional to 939.05, 1,408.58 and 391.85 is: 587.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.05 : 1,408.58 = 391.85 : x
  2. Step 2: Convert to fraction form
    939.05/1,408.58 = 391.85/x
  3. Step 3: Cross multiply
    939.05x = 1,408.58 × 391.85
  4. Step 4: Simplify right side
    939.05x = 551,952.07
  5. Step 5: Solve for x
    x = 551,952.07/939.05
  6. Step 6: Final answer
    x = 587.78

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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.