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Finding the Fourth Proportional to 129.21, 178.14 and 111.90

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Solution

The fourth proportional to 129.21, 178.14 and 111.90 is: 154.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.21 : 178.14 = 111.90 : x
  2. Step 2: Convert to fraction form
    129.21/178.14 = 111.90/x
  3. Step 3: Cross multiply
    129.21x = 178.14 × 111.90
  4. Step 4: Simplify right side
    129.21x = 19,933.87
  5. Step 5: Solve for x
    x = 19,933.87/129.21
  6. Step 6: Final answer
    x = 154.27

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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.