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Finding the Fourth Proportional to 129.38, 178.46 and 80.21

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Solution

The fourth proportional to 129.38, 178.46 and 80.21 is: 110.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.38 : 178.46 = 80.21 : x
  2. Step 2: Convert to fraction form
    129.38/178.46 = 80.21/x
  3. Step 3: Cross multiply
    129.38x = 178.46 × 80.21
  4. Step 4: Simplify right side
    129.38x = 14,312.98
  5. Step 5: Solve for x
    x = 14,312.98/129.38
  6. Step 6: Final answer
    x = 110.63

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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.