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Finding the Fourth Proportional to 129.48, 178.74 and 85.20

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Solution

The fourth proportional to 129.48, 178.74 and 85.20 is: 117.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.48 : 178.74 = 85.20 : x
  2. Step 2: Convert to fraction form
    129.48/178.74 = 85.20/x
  3. Step 3: Cross multiply
    129.48x = 178.74 × 85.20
  4. Step 4: Simplify right side
    129.48x = 15,228.65
  5. Step 5: Solve for x
    x = 15,228.65/129.48
  6. Step 6: Final answer
    x = 117.61

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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.