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Finding the Fourth Proportional to 128.54, 192.78 and 109.28

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Solution

The fourth proportional to 128.54, 192.78 and 109.28 is: 163.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.54 : 192.78 = 109.28 : x
  2. Step 2: Convert to fraction form
    128.54/192.78 = 109.28/x
  3. Step 3: Cross multiply
    128.54x = 192.78 × 109.28
  4. Step 4: Simplify right side
    128.54x = 21,067.00
  5. Step 5: Solve for x
    x = 21,067.00/128.54
  6. Step 6: Final answer
    x = 163.89

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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.