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Finding the Fourth Proportional to 938.71, 1,408.12 and 390.93

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Solution

The fourth proportional to 938.71, 1,408.12 and 390.93 is: 586.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.71 : 1,408.12 = 390.93 : x
  2. Step 2: Convert to fraction form
    938.71/1,408.12 = 390.93/x
  3. Step 3: Cross multiply
    938.71x = 1,408.12 × 390.93
  4. Step 4: Simplify right side
    938.71x = 550,476.35
  5. Step 5: Solve for x
    x = 550,476.35/938.71
  6. Step 6: Final answer
    x = 586.42

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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.