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Finding the Fourth Proportional to 20.87, 31.30 and 8.85

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Solution

The fourth proportional to 20.87, 31.30 and 8.85 is: 13.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.87 : 31.30 = 8.85 : x
  2. Step 2: Convert to fraction form
    20.87/31.30 = 8.85/x
  3. Step 3: Cross multiply
    20.87x = 31.30 × 8.85
  4. Step 4: Simplify right side
    20.87x = 276.96
  5. Step 5: Solve for x
    x = 276.96/20.87
  6. Step 6: Final answer
    x = 13.27

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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.