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Finding the Fourth Proportional to 138.76, 207.90 and 87.24

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Solution

The fourth proportional to 138.76, 207.90 and 87.24 is: 130.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.76 : 207.90 = 87.24 : x
  2. Step 2: Convert to fraction form
    138.76/207.90 = 87.24/x
  3. Step 3: Cross multiply
    138.76x = 207.90 × 87.24
  4. Step 4: Simplify right side
    138.76x = 18,137.20
  5. Step 5: Solve for x
    x = 18,137.20/138.76
  6. Step 6: Final answer
    x = 130.71

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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.