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Finding the Fourth Proportional to 20.87, 31.31 and 9.47

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Solution

The fourth proportional to 20.87, 31.31 and 9.47 is: 14.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.87 : 31.31 = 9.47 : x
  2. Step 2: Convert to fraction form
    20.87/31.31 = 9.47/x
  3. Step 3: Cross multiply
    20.87x = 31.31 × 9.47
  4. Step 4: Simplify right side
    20.87x = 296.30
  5. Step 5: Solve for x
    x = 296.30/20.87
  6. Step 6: Final answer
    x = 14.20

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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.