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Finding the Fourth Proportional to 128.22, 192.36 and 81.36

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Solution

The fourth proportional to 128.22, 192.36 and 81.36 is: 122.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.22 : 192.36 = 81.36 : x
  2. Step 2: Convert to fraction form
    128.22/192.36 = 81.36/x
  3. Step 3: Cross multiply
    128.22x = 192.36 × 81.36
  4. Step 4: Simplify right side
    128.22x = 15,650.41
  5. Step 5: Solve for x
    x = 15,650.41/128.22
  6. Step 6: Final answer
    x = 122.06

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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.