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Finding the Fourth Proportional to 129.16, 178.24 and 76.72

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Solution

The fourth proportional to 129.16, 178.24 and 76.72 is: 105.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.16 : 178.24 = 76.72 : x
  2. Step 2: Convert to fraction form
    129.16/178.24 = 76.72/x
  3. Step 3: Cross multiply
    129.16x = 178.24 × 76.72
  4. Step 4: Simplify right side
    129.16x = 13,674.57
  5. Step 5: Solve for x
    x = 13,674.57/129.16
  6. Step 6: Final answer
    x = 105.87

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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.