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Finding the Fourth Proportional to 81.74, 112.70 and 57.20

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Solution

The fourth proportional to 81.74, 112.70 and 57.20 is: 78.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.74 : 112.70 = 57.20 : x
  2. Step 2: Convert to fraction form
    81.74/112.70 = 57.20/x
  3. Step 3: Cross multiply
    81.74x = 112.70 × 57.20
  4. Step 4: Simplify right side
    81.74x = 6,446.02
  5. Step 5: Solve for x
    x = 6,446.02/81.74
  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.