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Finding the Fourth Proportional to 13.78, 20.55 and 12.65

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Solution

The fourth proportional to 13.78, 20.55 and 12.65 is: 18.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.78 : 20.55 = 12.65 : x
  2. Step 2: Convert to fraction form
    13.78/20.55 = 12.65/x
  3. Step 3: Cross multiply
    13.78x = 20.55 × 12.65
  4. Step 4: Simplify right side
    13.78x = 259.90
  5. Step 5: Solve for x
    x = 259.90/13.78
  6. Step 6: Final answer
    x = 18.86

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.