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Finding the Fourth Proportional to 129.12, 178.02 and 105.72

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Solution

The fourth proportional to 129.12, 178.02 and 105.72 is: 145.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.12 : 178.02 = 105.72 : x
  2. Step 2: Convert to fraction form
    129.12/178.02 = 105.72/x
  3. Step 3: Cross multiply
    129.12x = 178.02 × 105.72
  4. Step 4: Simplify right side
    129.12x = 18,820.27
  5. Step 5: Solve for x
    x = 18,820.27/129.12
  6. Step 6: Final answer
    x = 145.76

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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.