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Finding the Fourth Proportional to 938.62, 1,408.02 and 390.70

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Solution

The fourth proportional to 938.62, 1,408.02 and 390.70 is: 586.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.62 : 1,408.02 = 390.70 : x
  2. Step 2: Convert to fraction form
    938.62/1,408.02 = 390.70/x
  3. Step 3: Cross multiply
    938.62x = 1,408.02 × 390.70
  4. Step 4: Simplify right side
    938.62x = 550,113.41
  5. Step 5: Solve for x
    x = 550,113.41/938.62
  6. Step 6: Final answer
    x = 586.09

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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.