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Finding the Fourth Proportional to 21.54, 29.72 and 20.86

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Solution

The fourth proportional to 21.54, 29.72 and 20.86 is: 28.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.54 : 29.72 = 20.86 : x
  2. Step 2: Convert to fraction form
    21.54/29.72 = 20.86/x
  3. Step 3: Cross multiply
    21.54x = 29.72 × 20.86
  4. Step 4: Simplify right side
    21.54x = 619.96
  5. Step 5: Solve for x
    x = 619.96/21.54
  6. Step 6: Final answer
    x = 28.79

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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.