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Finding the Fourth Proportional to 28.20, 42.31 and 12.18

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Solution

The fourth proportional to 28.20, 42.31 and 12.18 is: 18.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.20 : 42.31 = 12.18 : x
  2. Step 2: Convert to fraction form
    28.20/42.31 = 12.18/x
  3. Step 3: Cross multiply
    28.20x = 42.31 × 12.18
  4. Step 4: Simplify right side
    28.20x = 515.34
  5. Step 5: Solve for x
    x = 515.34/28.20
  6. Step 6: Final answer
    x = 18.27

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.