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Finding the Fourth Proportional to 12.21, 18.78 and 12.21

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Solution

The fourth proportional to 12.21, 18.78 and 12.21 is: 18.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    12.21 : 18.78 = 12.21 : x
  2. Step 2: Convert to fraction form
    12.21/18.78 = 12.21/x
  3. Step 3: Cross multiply
    12.21x = 18.78 × 12.21
  4. Step 4: Simplify right side
    12.21x = 229.30
  5. Step 5: Solve for x
    x = 229.30/12.21
  6. Step 6: Final answer
    x = 18.78

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Why These Related Problems?

These problems maintain the same ratio (1.54) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.