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Finding the Fourth Proportional to 129.76, 178.88 and 115.18

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Solution

The fourth proportional to 129.76, 178.88 and 115.18 is: 158.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.76 : 178.88 = 115.18 : x
  2. Step 2: Convert to fraction form
    129.76/178.88 = 115.18/x
  3. Step 3: Cross multiply
    129.76x = 178.88 × 115.18
  4. Step 4: Simplify right side
    129.76x = 20,603.40
  5. Step 5: Solve for x
    x = 20,603.40/129.76
  6. Step 6: Final answer
    x = 158.78

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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.