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Finding the Fourth Proportional to 28.12, 38.81 and 15.85

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Solution

The fourth proportional to 28.12, 38.81 and 15.85 is: 21.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.12 : 38.81 = 15.85 : x
  2. Step 2: Convert to fraction form
    28.12/38.81 = 15.85/x
  3. Step 3: Cross multiply
    28.12x = 38.81 × 15.85
  4. Step 4: Simplify right side
    28.12x = 615.09
  5. Step 5: Solve for x
    x = 615.09/28.12
  6. Step 6: Final answer
    x = 21.87

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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.