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Finding the Fourth Proportional to 20.98, 31.49 and 12.45

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Solution

The fourth proportional to 20.98, 31.49 and 12.45 is: 18.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.98 : 31.49 = 12.45 : x
  2. Step 2: Convert to fraction form
    20.98/31.49 = 12.45/x
  3. Step 3: Cross multiply
    20.98x = 31.49 × 12.45
  4. Step 4: Simplify right side
    20.98x = 392.15
  5. Step 5: Solve for x
    x = 392.15/20.98
  6. Step 6: Final answer
    x = 18.69

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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.