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Finding the Fourth Proportional to 129.78, 180.06 and 128.58

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Solution

The fourth proportional to 129.78, 180.06 and 128.58 is: 178.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.78 : 180.06 = 128.58 : x
  2. Step 2: Convert to fraction form
    129.78/180.06 = 128.58/x
  3. Step 3: Cross multiply
    129.78x = 180.06 × 128.58
  4. Step 4: Simplify right side
    129.78x = 23,152.11
  5. Step 5: Solve for x
    x = 23,152.11/129.78
  6. Step 6: Final answer
    x = 178.40

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.