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Finding the Fourth Proportional to 128.08, 192.16 and 81.84

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Solution

The fourth proportional to 128.08, 192.16 and 81.84 is: 122.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.08 : 192.16 = 81.84 : x
  2. Step 2: Convert to fraction form
    128.08/192.16 = 81.84/x
  3. Step 3: Cross multiply
    128.08x = 192.16 × 81.84
  4. Step 4: Simplify right side
    128.08x = 15,726.37
  5. Step 5: Solve for x
    x = 15,726.37/128.08
  6. Step 6: Final answer
    x = 122.79

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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.