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Finding the Fourth Proportional to 129.72, 178.98 and 80.64

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Solution

The fourth proportional to 129.72, 178.98 and 80.64 is: 111.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.72 : 178.98 = 80.64 : x
  2. Step 2: Convert to fraction form
    129.72/178.98 = 80.64/x
  3. Step 3: Cross multiply
    129.72x = 178.98 × 80.64
  4. Step 4: Simplify right side
    129.72x = 14,432.95
  5. Step 5: Solve for x
    x = 14,432.95/129.72
  6. Step 6: Final answer
    x = 111.26

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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.