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Finding the Fourth Proportional to 81.96, 122.70 and 68.20

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Solution

The fourth proportional to 81.96, 122.70 and 68.20 is: 102.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.96 : 122.70 = 68.20 : x
  2. Step 2: Convert to fraction form
    81.96/122.70 = 68.20/x
  3. Step 3: Cross multiply
    81.96x = 122.70 × 68.20
  4. Step 4: Simplify right side
    81.96x = 8,368.14
  5. Step 5: Solve for x
    x = 8,368.14/81.96
  6. Step 6: Final answer
    x = 102.10

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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.