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Finding the Fourth Proportional to 81.50, 122.13 and 42.92

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Solution

The fourth proportional to 81.50, 122.13 and 42.92 is: 64.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.50 : 122.13 = 42.92 : x
  2. Step 2: Convert to fraction form
    81.50/122.13 = 42.92/x
  3. Step 3: Cross multiply
    81.50x = 122.13 × 42.92
  4. Step 4: Simplify right side
    81.50x = 5,241.21
  5. Step 5: Solve for x
    x = 5,241.21/81.50
  6. Step 6: Final answer
    x = 64.31

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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.