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Finding the Fourth Proportional to 129.90, 179.18 and 77.42

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Solution

The fourth proportional to 129.90, 179.18 and 77.42 is: 106.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.90 : 179.18 = 77.42 : x
  2. Step 2: Convert to fraction form
    129.90/179.18 = 77.42/x
  3. Step 3: Cross multiply
    129.90x = 179.18 × 77.42
  4. Step 4: Simplify right side
    129.90x = 13,872.12
  5. Step 5: Solve for x
    x = 13,872.12/129.90
  6. Step 6: Final answer
    x = 106.79

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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.