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Finding the Fourth Proportional to 13.90, 20.79 and 8.39

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Solution

The fourth proportional to 13.90, 20.79 and 8.39 is: 12.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.90 : 20.79 = 8.39 : x
  2. Step 2: Convert to fraction form
    13.90/20.79 = 8.39/x
  3. Step 3: Cross multiply
    13.90x = 20.79 × 8.39
  4. Step 4: Simplify right side
    13.90x = 174.32
  5. Step 5: Solve for x
    x = 174.32/13.90
  6. Step 6: Final answer
    x = 12.55

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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.