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Finding the Fourth Proportional to 431.47, 647.05 and 138.96

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Solution

The fourth proportional to 431.47, 647.05 and 138.96 is: 208.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.47 : 647.05 = 138.96 : x
  2. Step 2: Convert to fraction form
    431.47/647.05 = 138.96/x
  3. Step 3: Cross multiply
    431.47x = 647.05 × 138.96
  4. Step 4: Simplify right side
    431.47x = 89,913.72
  5. Step 5: Solve for x
    x = 89,913.72/431.47
  6. Step 6: Final answer
    x = 208.39

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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.