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Finding the Fourth Proportional to 81.72, 112.71 and 57.18

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Solution

The fourth proportional to 81.72, 112.71 and 57.18 is: 78.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.72 : 112.71 = 57.18 : x
  2. Step 2: Convert to fraction form
    81.72/112.71 = 57.18/x
  3. Step 3: Cross multiply
    81.72x = 112.71 × 57.18
  4. Step 4: Simplify right side
    81.72x = 6,444.76
  5. Step 5: Solve for x
    x = 6,444.76/81.72
  6. Step 6: Final answer
    x = 78.86

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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.