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Finding the Fourth Proportional to 129.09, 178.20 and 85.46

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Solution

The fourth proportional to 129.09, 178.20 and 85.46 is: 117.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.09 : 178.20 = 85.46 : x
  2. Step 2: Convert to fraction form
    129.09/178.20 = 85.46/x
  3. Step 3: Cross multiply
    129.09x = 178.20 × 85.46
  4. Step 4: Simplify right side
    129.09x = 15,228.08
  5. Step 5: Solve for x
    x = 15,228.08/129.09
  6. Step 6: Final answer
    x = 117.96

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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.