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Finding the Fourth Proportional to 129.78, 179.18 and 86.16

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Solution

The fourth proportional to 129.78, 179.18 and 86.16 is: 118.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.78 : 179.18 = 86.16 : x
  2. Step 2: Convert to fraction form
    129.78/179.18 = 86.16/x
  3. Step 3: Cross multiply
    129.78x = 179.18 × 86.16
  4. Step 4: Simplify right side
    129.78x = 15,438.15
  5. Step 5: Solve for x
    x = 15,438.15/129.78
  6. Step 6: Final answer
    x = 118.96

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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.