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Finding the Fourth Proportional to 128.08, 192.12 and 67.20

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Solution

The fourth proportional to 128.08, 192.12 and 67.20 is: 100.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.08 : 192.12 = 67.20 : x
  2. Step 2: Convert to fraction form
    128.08/192.12 = 67.20/x
  3. Step 3: Cross multiply
    128.08x = 192.12 × 67.20
  4. Step 4: Simplify right side
    128.08x = 12,910.46
  5. Step 5: Solve for x
    x = 12,910.46/128.08
  6. Step 6: Final answer
    x = 100.80

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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.