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Finding the Fourth Proportional to 129.70, 178.86 and 77.92

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Solution

The fourth proportional to 129.70, 178.86 and 77.92 is: 107.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.70 : 178.86 = 77.92 : x
  2. Step 2: Convert to fraction form
    129.70/178.86 = 77.92/x
  3. Step 3: Cross multiply
    129.70x = 178.86 × 77.92
  4. Step 4: Simplify right side
    129.70x = 13,936.77
  5. Step 5: Solve for x
    x = 13,936.77/129.70
  6. Step 6: Final answer
    x = 107.45

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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.