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Finding the Fourth Proportional to 81.67, 112.76 and 77.80

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Solution

The fourth proportional to 81.67, 112.76 and 77.80 is: 107.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.67 : 112.76 = 77.80 : x
  2. Step 2: Convert to fraction form
    81.67/112.76 = 77.80/x
  3. Step 3: Cross multiply
    81.67x = 112.76 × 77.80
  4. Step 4: Simplify right side
    81.67x = 8,772.73
  5. Step 5: Solve for x
    x = 8,772.73/81.67
  6. Step 6: Final answer
    x = 107.42

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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.