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Finding the Fourth Proportional to 28.12, 38.81 and 21.64

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Solution

The fourth proportional to 28.12, 38.81 and 21.64 is: 29.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.12 : 38.81 = 21.64 : x
  2. Step 2: Convert to fraction form
    28.12/38.81 = 21.64/x
  3. Step 3: Cross multiply
    28.12x = 38.81 × 21.64
  4. Step 4: Simplify right side
    28.12x = 839.85
  5. Step 5: Solve for x
    x = 839.85/28.12
  6. Step 6: Final answer
    x = 29.87

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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.