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Finding the Fourth Proportional to 129.55, 178.68 and 77.80

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Solution

The fourth proportional to 129.55, 178.68 and 77.80 is: 107.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.55 : 178.68 = 77.80 : x
  2. Step 2: Convert to fraction form
    129.55/178.68 = 77.80/x
  3. Step 3: Cross multiply
    129.55x = 178.68 × 77.80
  4. Step 4: Simplify right side
    129.55x = 13,901.30
  5. Step 5: Solve for x
    x = 13,901.30/129.55
  6. Step 6: Final answer
    x = 107.30

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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.