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Finding the Fourth Proportional to 129.92, 179.64 and 121.76

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Solution

The fourth proportional to 129.92, 179.64 and 121.76 is: 168.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.92 : 179.64 = 121.76 : x
  2. Step 2: Convert to fraction form
    129.92/179.64 = 121.76/x
  3. Step 3: Cross multiply
    129.92x = 179.64 × 121.76
  4. Step 4: Simplify right side
    129.92x = 21,872.97
  5. Step 5: Solve for x
    x = 21,872.97/129.92
  6. Step 6: Final answer
    x = 168.36

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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.