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Finding the Fourth Proportional to 129.56, 192.80 and 128.20

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Solution

The fourth proportional to 129.56, 192.80 and 128.20 is: 190.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.56 : 192.80 = 128.20 : x
  2. Step 2: Convert to fraction form
    129.56/192.80 = 128.20/x
  3. Step 3: Cross multiply
    129.56x = 192.80 × 128.20
  4. Step 4: Simplify right side
    129.56x = 24,716.96
  5. Step 5: Solve for x
    x = 24,716.96/129.56
  6. Step 6: Final answer
    x = 190.78

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.