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Finding the Fourth Proportional to 138.18, 189.56 and 129.90

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Solution

The fourth proportional to 138.18, 189.56 and 129.90 is: 178.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.18 : 189.56 = 129.90 : x
  2. Step 2: Convert to fraction form
    138.18/189.56 = 129.90/x
  3. Step 3: Cross multiply
    138.18x = 189.56 × 129.90
  4. Step 4: Simplify right side
    138.18x = 24,623.19
  5. Step 5: Solve for x
    x = 24,623.19/138.18
  6. Step 6: Final answer
    x = 178.20

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.