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Finding the Fourth Proportional to 28.72, 39.57 and 20.92

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Solution

The fourth proportional to 28.72, 39.57 and 20.92 is: 28.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.72 : 39.57 = 20.92 : x
  2. Step 2: Convert to fraction form
    28.72/39.57 = 20.92/x
  3. Step 3: Cross multiply
    28.72x = 39.57 × 20.92
  4. Step 4: Simplify right side
    28.72x = 827.80
  5. Step 5: Solve for x
    x = 827.80/28.72
  6. Step 6: Final answer
    x = 28.82

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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.