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Finding the Fourth Proportional to 21.34, 29.39 and 20.87

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Solution

The fourth proportional to 21.34, 29.39 and 20.87 is: 28.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.34 : 29.39 = 20.87 : x
  2. Step 2: Convert to fraction form
    21.34/29.39 = 20.87/x
  3. Step 3: Cross multiply
    21.34x = 29.39 × 20.87
  4. Step 4: Simplify right side
    21.34x = 613.12
  5. Step 5: Solve for x
    x = 613.12/21.34
  6. Step 6: Final answer
    x = 28.73

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.