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Finding the Fourth Proportional to 129.40, 178.46 and 87.48

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Solution

The fourth proportional to 129.40, 178.46 and 87.48 is: 120.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.40 : 178.46 = 87.48 : x
  2. Step 2: Convert to fraction form
    129.40/178.46 = 87.48/x
  3. Step 3: Cross multiply
    129.40x = 178.46 × 87.48
  4. Step 4: Simplify right side
    129.40x = 15,611.68
  5. Step 5: Solve for x
    x = 15,611.68/129.40
  6. Step 6: Final answer
    x = 120.65

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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.