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Finding the Fourth Proportional to 81.28, 112.14 and 56.39

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Solution

The fourth proportional to 81.28, 112.14 and 56.39 is: 77.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.28 : 112.14 = 56.39 : x
  2. Step 2: Convert to fraction form
    81.28/112.14 = 56.39/x
  3. Step 3: Cross multiply
    81.28x = 112.14 × 56.39
  4. Step 4: Simplify right side
    81.28x = 6,323.85
  5. Step 5: Solve for x
    x = 6,323.85/81.28
  6. Step 6: Final answer
    x = 77.81

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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.