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Finding the Fourth Proportional to 81.90, 122.23 and 79.86

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Solution

The fourth proportional to 81.90, 122.23 and 79.86 is: 119.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.90 : 122.23 = 79.86 : x
  2. Step 2: Convert to fraction form
    81.90/122.23 = 79.86/x
  3. Step 3: Cross multiply
    81.90x = 122.23 × 79.86
  4. Step 4: Simplify right side
    81.90x = 9,761.09
  5. Step 5: Solve for x
    x = 9,761.09/81.90
  6. Step 6: Final answer
    x = 119.18

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.