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Finding the Fourth Proportional to 129.56, 178.74 and 77.72

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Solution

The fourth proportional to 129.56, 178.74 and 77.72 is: 107.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.56 : 178.74 = 77.72 : x
  2. Step 2: Convert to fraction form
    129.56/178.74 = 77.72/x
  3. Step 3: Cross multiply
    129.56x = 178.74 × 77.72
  4. Step 4: Simplify right side
    129.56x = 13,891.67
  5. Step 5: Solve for x
    x = 13,891.67/129.56
  6. Step 6: Final answer
    x = 107.22

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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.