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Finding the Fourth Proportional to 81.57, 122.48 and 66.21

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Solution

The fourth proportional to 81.57, 122.48 and 66.21 is: 99.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.57 : 122.48 = 66.21 : x
  2. Step 2: Convert to fraction form
    81.57/122.48 = 66.21/x
  3. Step 3: Cross multiply
    81.57x = 122.48 × 66.21
  4. Step 4: Simplify right side
    81.57x = 8,108.86
  5. Step 5: Solve for x
    x = 8,108.86/81.57
  6. Step 6: Final answer
    x = 99.41

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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.