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Finding the Fourth Proportional to 128.11, 192.09 and 76.68

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Solution

The fourth proportional to 128.11, 192.09 and 76.68 is: 114.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.11 : 192.09 = 76.68 : x
  2. Step 2: Convert to fraction form
    128.11/192.09 = 76.68/x
  3. Step 3: Cross multiply
    128.11x = 192.09 × 76.68
  4. Step 4: Simplify right side
    128.11x = 14,729.46
  5. Step 5: Solve for x
    x = 14,729.46/128.11
  6. Step 6: Final answer
    x = 114.98

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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.