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Finding the Fourth Proportional to 128.94, 178.11 and 122.87

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Solution

The fourth proportional to 128.94, 178.11 and 122.87 is: 169.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.94 : 178.11 = 122.87 : x
  2. Step 2: Convert to fraction form
    128.94/178.11 = 122.87/x
  3. Step 3: Cross multiply
    128.94x = 178.11 × 122.87
  4. Step 4: Simplify right side
    128.94x = 21,883.49
  5. Step 5: Solve for x
    x = 21,883.49/128.94
  6. Step 6: Final answer
    x = 169.72

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.