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Finding the Fourth Proportional to 138.61, 207.81 and 51.90

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Solution

The fourth proportional to 138.61, 207.81 and 51.90 is: 77.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.61 : 207.81 = 51.90 : x
  2. Step 2: Convert to fraction form
    138.61/207.81 = 51.90/x
  3. Step 3: Cross multiply
    138.61x = 207.81 × 51.90
  4. Step 4: Simplify right side
    138.61x = 10,785.34
  5. Step 5: Solve for x
    x = 10,785.34/138.61
  6. Step 6: Final answer
    x = 77.81

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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.