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Finding the Fourth Proportional to 128.92, 178.26 and 120.76

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Solution

The fourth proportional to 128.92, 178.26 and 120.76 is: 166.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.92 : 178.26 = 120.76 : x
  2. Step 2: Convert to fraction form
    128.92/178.26 = 120.76/x
  3. Step 3: Cross multiply
    128.92x = 178.26 × 120.76
  4. Step 4: Simplify right side
    128.92x = 21,526.68
  5. Step 5: Solve for x
    x = 21,526.68/128.92
  6. Step 6: Final answer
    x = 166.98

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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.