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Finding the Fourth Proportional to 28.72, 39.64 and 20.16

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Solution

The fourth proportional to 28.72, 39.64 and 20.16 is: 27.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.72 : 39.64 = 20.16 : x
  2. Step 2: Convert to fraction form
    28.72/39.64 = 20.16/x
  3. Step 3: Cross multiply
    28.72x = 39.64 × 20.16
  4. Step 4: Simplify right side
    28.72x = 799.14
  5. Step 5: Solve for x
    x = 799.14/28.72
  6. Step 6: Final answer
    x = 27.83

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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.