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Finding the Fourth Proportional to 21.13, 29.13 and 20.86

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Solution

The fourth proportional to 21.13, 29.13 and 20.86 is: 28.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.13 : 29.13 = 20.86 : x
  2. Step 2: Convert to fraction form
    21.13/29.13 = 20.86/x
  3. Step 3: Cross multiply
    21.13x = 29.13 × 20.86
  4. Step 4: Simplify right side
    21.13x = 607.65
  5. Step 5: Solve for x
    x = 607.65/21.13
  6. Step 6: Final answer
    x = 28.76

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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.