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Finding the Fourth Proportional to 129.12, 192.42 and 128.90

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Solution

The fourth proportional to 129.12, 192.42 and 128.90 is: 192.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.12 : 192.42 = 128.90 : x
  2. Step 2: Convert to fraction form
    129.12/192.42 = 128.90/x
  3. Step 3: Cross multiply
    129.12x = 192.42 × 128.90
  4. Step 4: Simplify right side
    129.12x = 24,802.94
  5. Step 5: Solve for x
    x = 24,802.94/129.12
  6. Step 6: Final answer
    x = 192.09

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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.