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Finding the Fourth Proportional to 129.33, 178.56 and 87.90

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Solution

The fourth proportional to 129.33, 178.56 and 87.90 is: 121.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.33 : 178.56 = 87.90 : x
  2. Step 2: Convert to fraction form
    129.33/178.56 = 87.90/x
  3. Step 3: Cross multiply
    129.33x = 178.56 × 87.90
  4. Step 4: Simplify right side
    129.33x = 15,695.42
  5. Step 5: Solve for x
    x = 15,695.42/129.33
  6. Step 6: Final answer
    x = 121.36

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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.