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Finding the Fourth Proportional to 81.16, 121.84 and 69.20

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Solution

The fourth proportional to 81.16, 121.84 and 69.20 is: 103.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.16 : 121.84 = 69.20 : x
  2. Step 2: Convert to fraction form
    81.16/121.84 = 69.20/x
  3. Step 3: Cross multiply
    81.16x = 121.84 × 69.20
  4. Step 4: Simplify right side
    81.16x = 8,431.33
  5. Step 5: Solve for x
    x = 8,431.33/81.16
  6. Step 6: Final answer
    x = 103.89

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.