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Finding the Fourth Proportional to 129.55, 178.80 and 74.31

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Solution

The fourth proportional to 129.55, 178.80 and 74.31 is: 102.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.55 : 178.80 = 74.31 : x
  2. Step 2: Convert to fraction form
    129.55/178.80 = 74.31/x
  3. Step 3: Cross multiply
    129.55x = 178.80 × 74.31
  4. Step 4: Simplify right side
    129.55x = 13,286.63
  5. Step 5: Solve for x
    x = 13,286.63/129.55
  6. Step 6: Final answer
    x = 102.56

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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.