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Finding the Fourth Proportional to 129.59, 178.85 and 77.15

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Solution

The fourth proportional to 129.59, 178.85 and 77.15 is: 106.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.59 : 178.85 = 77.15 : x
  2. Step 2: Convert to fraction form
    129.59/178.85 = 77.15/x
  3. Step 3: Cross multiply
    129.59x = 178.85 × 77.15
  4. Step 4: Simplify right side
    129.59x = 13,797.95
  5. Step 5: Solve for x
    x = 13,797.95/129.59
  6. Step 6: Final answer
    x = 106.47

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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.