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Finding the Fourth Proportional to 81.74, 112.74 and 57.12

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Solution

The fourth proportional to 81.74, 112.74 and 57.12 is: 78.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.74 : 112.74 = 57.12 : x
  2. Step 2: Convert to fraction form
    81.74/112.74 = 57.12/x
  3. Step 3: Cross multiply
    81.74x = 112.74 × 57.12
  4. Step 4: Simplify right side
    81.74x = 6,439.71
  5. Step 5: Solve for x
    x = 6,439.71/81.74
  6. Step 6: Final answer
    x = 78.78

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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.