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Finding the Fourth Proportional to 128.35, 177.25 and 81.76

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Solution

The fourth proportional to 128.35, 177.25 and 81.76 is: 112.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.35 : 177.25 = 81.76 : x
  2. Step 2: Convert to fraction form
    128.35/177.25 = 81.76/x
  3. Step 3: Cross multiply
    128.35x = 177.25 × 81.76
  4. Step 4: Simplify right side
    128.35x = 14,491.96
  5. Step 5: Solve for x
    x = 14,491.96/128.35
  6. Step 6: Final answer
    x = 112.91

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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.