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Finding the Fourth Proportional to 129.10, 178.20 and 76.66

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Solution

The fourth proportional to 129.10, 178.20 and 76.66 is: 105.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.10 : 178.20 = 76.66 : x
  2. Step 2: Convert to fraction form
    129.10/178.20 = 76.66/x
  3. Step 3: Cross multiply
    129.10x = 178.20 × 76.66
  4. Step 4: Simplify right side
    129.10x = 13,660.81
  5. Step 5: Solve for x
    x = 13,660.81/129.10
  6. Step 6: Final answer
    x = 105.82

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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.