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Finding the Fourth Proportional to 938.68, 1,408.64 and 390.86

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Solution

The fourth proportional to 938.68, 1,408.64 and 390.86 is: 586.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.68 : 1,408.64 = 390.86 : x
  2. Step 2: Convert to fraction form
    938.68/1,408.64 = 390.86/x
  3. Step 3: Cross multiply
    938.68x = 1,408.64 × 390.86
  4. Step 4: Simplify right side
    938.68x = 550,581.03
  5. Step 5: Solve for x
    x = 550,581.03/938.68
  6. Step 6: Final answer
    x = 586.55

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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.