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Finding the Fourth Proportional to 129.56, 194.40 and 78.20

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Solution

The fourth proportional to 129.56, 194.40 and 78.20 is: 117.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.56 : 194.40 = 78.20 : x
  2. Step 2: Convert to fraction form
    129.56/194.40 = 78.20/x
  3. Step 3: Cross multiply
    129.56x = 194.40 × 78.20
  4. Step 4: Simplify right side
    129.56x = 15,202.08
  5. Step 5: Solve for x
    x = 15,202.08/129.56
  6. Step 6: Final answer
    x = 117.34

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.