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Finding the Fourth Proportional to 138.76, 207.81 and 77.74

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Solution

The fourth proportional to 138.76, 207.81 and 77.74 is: 116.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.76 : 207.81 = 77.74 : x
  2. Step 2: Convert to fraction form
    138.76/207.81 = 77.74/x
  3. Step 3: Cross multiply
    138.76x = 207.81 × 77.74
  4. Step 4: Simplify right side
    138.76x = 16,154.63
  5. Step 5: Solve for x
    x = 16,154.63/138.76
  6. Step 6: Final answer
    x = 116.42

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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.