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Finding the Fourth Proportional to 138.96, 207.92 and 87.36

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Solution

The fourth proportional to 138.96, 207.92 and 87.36 is: 130.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.96 : 207.92 = 87.36 : x
  2. Step 2: Convert to fraction form
    138.96/207.92 = 87.36/x
  3. Step 3: Cross multiply
    138.96x = 207.92 × 87.36
  4. Step 4: Simplify right side
    138.96x = 18,163.45
  5. Step 5: Solve for x
    x = 18,163.45/138.96
  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.