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Finding the Fourth Proportional to 81.80, 122.70 and 20.93

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Solution

The fourth proportional to 81.80, 122.70 and 20.93 is: 31.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.80 : 122.70 = 20.93 : x
  2. Step 2: Convert to fraction form
    81.80/122.70 = 20.93/x
  3. Step 3: Cross multiply
    81.80x = 122.70 × 20.93
  4. Step 4: Simplify right side
    81.80x = 2,568.01
  5. Step 5: Solve for x
    x = 2,568.01/81.80
  6. Step 6: Final answer
    x = 31.39

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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.