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Finding the Fourth Proportional to 129.60, 178.76 and 80.40

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Solution

The fourth proportional to 129.60, 178.76 and 80.40 is: 110.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.60 : 178.76 = 80.40 : x
  2. Step 2: Convert to fraction form
    129.60/178.76 = 80.40/x
  3. Step 3: Cross multiply
    129.60x = 178.76 × 80.40
  4. Step 4: Simplify right side
    129.60x = 14,372.30
  5. Step 5: Solve for x
    x = 14,372.30/129.60
  6. Step 6: Final answer
    x = 110.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.