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Finding the Fourth Proportional to 128.63, 177.38 and 81.92

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Solution

The fourth proportional to 128.63, 177.38 and 81.92 is: 112.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.63 : 177.38 = 81.92 : x
  2. Step 2: Convert to fraction form
    128.63/177.38 = 81.92/x
  3. Step 3: Cross multiply
    128.63x = 177.38 × 81.92
  4. Step 4: Simplify right side
    128.63x = 14,529.67
  5. Step 5: Solve for x
    x = 14,529.67/128.63
  6. Step 6: Final answer
    x = 112.96

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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.