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Finding the Fourth Proportional to 938.70, 1,408.08 and 390.51

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Solution

The fourth proportional to 938.70, 1,408.08 and 390.51 is: 585.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.70 : 1,408.08 = 390.51 : x
  2. Step 2: Convert to fraction form
    938.70/1,408.08 = 390.51/x
  3. Step 3: Cross multiply
    938.70x = 1,408.08 × 390.51
  4. Step 4: Simplify right side
    938.70x = 549,869.32
  5. Step 5: Solve for x
    x = 549,869.32/938.70
  6. Step 6: Final answer
    x = 585.78

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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.