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Finding the Fourth Proportional to 129.21, 178.41 and 113.85

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Solution

The fourth proportional to 129.21, 178.41 and 113.85 is: 157.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.21 : 178.41 = 113.85 : x
  2. Step 2: Convert to fraction form
    129.21/178.41 = 113.85/x
  3. Step 3: Cross multiply
    129.21x = 178.41 × 113.85
  4. Step 4: Simplify right side
    129.21x = 20,311.98
  5. Step 5: Solve for x
    x = 20,311.98/129.21
  6. Step 6: Final answer
    x = 157.20

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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.